Compressor

ABSTRACT

A compressor which is inexpensive and highly reliable and capable of efficiently and securely drawing up oil in a stable manner even at the time of low-revolution driving is provided. Also, a compressor which is highly reliable and capable of maintaining the structure of a viscous pump in a stable condition for a long period is provided. The compressor has a closed container which stores oil and accommodates a compressing element for compressing gas. The compressing element includes a shaft which vertically extends and rotates and a viscous pump which communicates with oil.

TECHNICAL FIELD

The present invention relates to an improvement of a viscous pump forsupplying oil to sliding areas of a compressor.

BACKGROUND ART

Recently, household refrigerators and air-conditioners have beenincreasingly and rapidly shifting to energy-saving types to meet demandsfor protection of the global environment. In this situation, increasingnumbers of refrigerant compressors are inverter-controlled, and thenumber of driving revolution is decreased to reduce the rotationalspeed. Accordingly, it is difficult to obtain sufficient lubrication byusing conventional centrifugal pumps.

A conventional compressor, which is disclosed in JP-T-2002-519589, forexample, includes a viscous pump which has stable pumping capabilityeven at the time of low-speed revolution in lieu of a centrifugal pump.

The related-art compressor mentioned above is herein described withreference to the drawings. In this description, the positionalcorrelations in the vertical direction are shown based on the conditionin which a closed type electrically-powered compressor is installed in anormal position.

FIG. 34 is a cross-sectional view illustrating a main part of aconventional compressor. In FIG. 34, oil 7102 is stored in the bottomarea of closed container 7101. Electrically-powered element 7105includes stator 7106 and rotor 7107 which contains permanent magnet.Rotor 7107 engages with hollow shaft 7111 of compressing element 7110,and sleeve 7112 which is soaked with oil 7102 at least at its lower endand rotates integrally with shaft 7111 is fixed to shaft 7111.

Substantially U-shaped bracket 7115 made from elastic material has aconcave center portion and its both ends are fixed to shroud 7116secured to stator 7106. Insertion member 7120 made from plastic materialand inserted into sleeve 7112 has a spiral groove on its outer surfaceto provide oil passage between insertion member 7120 and sleeve 7112.The lower end of insertion member 7120 is fixed to the center portion ofbracket 7115.

The operation of the conventional compressor having the above structureis now described.

When electrically-powered element 7105 is energized, rotor 7107 rotates.Shaft 7111 revolves with the rotation of rotor 7107, and compressingelement 7110 carries out predetermined compressing operations. Oil 7102rises through the oil passage formed between the spiral groove formed onthe outer surface of insertion member 7120 and sleeve 7112 in accordancewith the revolution of sleeve 7112 while rotating and being pulled bythe inner surface of the sleeve due to viscosity, thereby drawing up oil7102 toward the upper hollow region of shaft 7111.

DISCLOSURE OF THE INVENTION

A compressor has a closed container which stores oil and accommodates acompressing element for compressing refrigerant and anelectrically-powered element for driving the compressing element,wherein: the electrically-powered element includes a stator and a rotor;and the compressing element includes a shaft which extends in a verticaldirection and rotates, and a viscous pump which is formed inside theshaft and communicates with the oil, the viscous pump having acylindrical hollow portion formed in the shaft, an insertion membercoaxially and rotatably inserted into the cylindrical hollow portion, aspiral groove formed between the inner surface of the cylindrical hollowportion and the outer surface of the insertion member along a directionwhere the oil rises, and prevention means for preventing rotation of theinsertion member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a main part of acompressor in a first embodiment of the present invention.

FIG. 2 is a perspective view of a lower part of a shaft in the firstembodiment of the invention.

FIG. 3 is a cross-sectional view illustrating the main part of thecompressor in a driving condition immediately after start-up in thefirst embodiment of the invention.

FIG. 4 is a cross-sectional view illustrating a main part of acompressor in a second embodiment of the invention.

FIG. 5 is a perspective view of a lower part of a shaft in the secondembodiment of the invention.

FIG. 6 is a cross-sectional enlarged view illustrating a sleeve in thesecond embodiment of the invention.

FIG. 7 is a cross-sectional view illustrating a main part of acompressor in a third embodiment of the invention.

FIG. 8 is a perspective view of a lower part of a shaft in the thirdembodiment of the invention.

FIG. 9 is a cross-sectional enlarged view illustrating a sleeve in thethird embodiment of the invention.

FIG. 10 is a cross-sectional view illustrating a compressor in a fourthembodiment of the invention.

FIG. 11 is a cross-sectional view illustrating a main part of thecompressor in the fourth embodiment of the invention.

FIG. 12 is a perspective view illustrating the main part of thecompressor in the fourth embodiment of the invention.

FIG. 13 is a cross-sectional view illustrating a main part of acompressor in a fifth embodiment of the invention.

FIG. 14 is a cross-sectional view illustrating a main part of acompressor in a sixth embodiment of the invention.

FIG. 15 is a cross-sectional view of a compressor in a seventhembodiment of the invention.

FIG. 16 is a cross-sectional view illustrating a main part of thecompressor in the seventh embodiment of the invention.

FIG. 17 is a cross-sectional view illustrating a main part of acompressor in an eighth embodiment of the invention.

FIG. 18 is a main part assembly view of the compressor in the eighthembodiment of the invention.

FIG. 19 is a cross-sectional view illustrating a compressor in a ninthembodiment of the invention.

FIG. 20 is a cross-sectional view illustrating a main part of thecompressor in the ninth embodiment of the invention.

FIG. 21 is a cross-sectional view illustrating a compressor in a tenthembodiment of the invention.

FIG. 22 is a cross-sectional view illustrating a main part of thecompressor in the tenth embodiment of the invention.

FIG. 23 is a cross-sectional view illustrating a compressor in aneleventh embodiment of the invention.

FIG. 24 is a cross-sectional view illustrating a main part of thecompressor in the eleventh embodiment of the invention.

FIG. 25 is an enlarged view illustrating a main part of an insertionmember in the eleventh embodiment of the invention.

FIG. 26 is a cross-sectional view illustrating a compressor in a twelfthembodiment of the invention.

FIG. 27 is a cross-sectional view illustrating a main part of thecompressor in the twelfth embodiment of the invention.

FIG. 28 is a cross-sectional view illustrating a compressor in athirteenth embodiment of the invention.

FIG. 29 is a cross-sectional view illustrating a main part of thecompressor in the thirteenth embodiment of the invention.

FIG. 30 is a cross-sectional view illustrating a compressor in afourteenth embodiment of the invention.

FIG. 31 is a cross-sectional view illustrating a main part of thecompressor in the fourteenth embodiment of the invention.

FIG. 32 is a cross-sectional view illustrating a main part of a viscouspump in the fourteenth embodiment of the invention.

FIG. 33 is a cross-sectional view illustrating a main part of acompressor in a fifteenth embodiment of the invention.

FIG. 34 is a cross-sectional view illustrating a main part of aconventional compressor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the description of the structure of the above-describedconventional compressor, a hollow opening is provided in an upper areaof the viscous pump, and there is a large space for storing transferredoil. Especially, the process for further raising oil drawn by theviscous pump immediately after the start-up requires sufficient time forstoring oil until the hollow opening is substantially filled with oil.

As a result, oil is transferred upward at lower speed and thus oilsupply to sliding areas becomes unstable. This causes sliding componentsto contact each other while sliding, forming scratches and abrasiontherebetween. These damages lead to a locked condition of thecompressing element.

In order to solve the above problem, an object of the present inventionis to provide a highly reliable compressor which transfers oil to eachsliding area at high speed and has reliable and stable oil transfercapability even at the time of low-speed driving.

For achieving the above object, a compressor of the present inventionincludes a viscous pump which opens to oil stored in a lower region of aclosed container and a second viscous pump connected to an upper regionof the former viscous pump, both the viscous pumps being attached to amain shaft portion of a shaft. Since most area of an oil passage in themain shaft portion is occupied by the pumps, the space for storing oiland refrigerant is reduced. Consequently, the oil transfer speedincreases. Additionally, oil receives not only centrifugal force whichdecreases at the time of low-speed revolution but also upward pressurewhile being pulled due to viscosity within the passage.

The compressor provided according to the present invention, whichincludes a viscous pump and a second viscous pump disposed above theviscous pump, is a highly reliable compressor which transfers oil athigh speed and has stable oil transfer capability even at the time oflow-speed driving.

First through third embodiments of the present invention is hereinafterdescribed with reference to the drawings. The present invention is notlimited to those embodiments.

Embodiment 1

FIG. 1 is a cross-sectional view illustrating a main part of acompressor in the first embodiment of the invention, FIG. 2 is aperspective view of a lower part of a shaft in the first embodiment, andFIG. 3 is a cross-sectional view illustrating the main part of thecompressor in a driving condition immediately after start-up in thefirst embodiment.

In FIGS. 1, 2 and 3, oil 3102 is stored in closed container 3101 whichis charged with refrigerant 3103.

Compressing element 3110 includes: block 3109 which forms cylinder 3108;piston 3113 reciprocatively inserted into cylinder 3108; shaft 3111having main shaft portion 3116 supported by main bearing 3114 of block3109 and eccentric portion 3117; and connecting rod 3118 for connectingeccentric portion 3117 and piston 3113. Compressing element 3110 forms areciprocating compressing mechanism.

Electrically-powered element 105 is fixed below block 3109.Electrically-powered element 105 includes stator 3106 connected to aninverter driving circuit (not shown) and rotor 3107 which containspermanent magnet (not shown) and is fixed to main shaft portion 3116.Electrically-powered element 105 is an electrically-powered element 105for driving the inverter, and is driven at a plurality of drivingfrequencies including those at least in a range from 600 to 1,200 r/min.by the inverter driving circuit.

Springs 3104 elastically support compressing element 3110 via stator3106 so that compressing element 3110 is elastically held on closedcontainer 3101.

Main shaft portion 3116 of shaft 3111 has viscous pump 3130 soaked withoil 3102 and second viscous pump 3150 connected with viscous pump 3130through communicating hole 3140. Second viscous pump 3150 is disposedabove viscous pump 3130.

Next, the structures of viscous pump 3130 and second viscous pump 3150connected with each other are described in detail.

Viscous pump 3130 includes: cylindrical hollow portion 3135 formed inmain shaft portion 3116; sleeve 3131 secured to the lower region ofcylindrical hollow portion 3135; insertion member 3133 coaxiallyinserted into cylindrical hollow portion 3135 and sleeve 3131; andsupporting member 3132. Supporting member 3132 has restricting means3139 for restricting floating of insertion member 3133 in the rotationaland vertical directions.

The upper end of cylindrical hollow portion 3135 reaches the lowerregion of main bearing 3114.

Sleeve 3131 is substantially cylindrical and cap-shaped, whose top andbottom are open. Sleeve 3131 is made from iron plate press materialwhich offers comparatively high accuracy, but may be formed from leafspring steel.

Thread-shaped spiral groove 3134 is formed on the outer surface ofinsertion member 3133 to provide a spiral oil passage between spiralgroove 3134 and sleeve 3131, through which passage oil 3102 is allowedto flow. Insertion member 3133 has refrigerant-resistance andoil-resistance properties, and is made from plastic material havinglower thermal conductivity than the metal material which forms shaft3111, such as PPS, PBT, and PEEK.

Supporting member 3132 is substantially U-shaped and made from elasticmaterial such as iron spring wire. Both ends of supporting member 3132are fixed to the lower position of stator 3106. The center portion ofsupporting member 3132 engages with engagement holes 3137 throughnotches 3136 provided at the lower end of insertion member 3133. Notches3136 are disposed before engagement holes 3137 in the advancingdirection of main bearing 3114 and joined with engagement holes 3137.The length of joining portions 3138 of engagement holes 3137, i.e., thelength of the openings in contact with notches 3136 is smaller than theoutside diameter of supporting member 3132.

Second viscous pump 3150 includes main shaft portion 3116, lead groove3151 engraved on the outer surface of main shaft portion 3116, and mainbearing 3114.

Main bearing 3114 is secured to block 3109, or formed integrally withblock 3109 to be secured thereto. Lead groove 3151 having a trapezoidalor substantially semicircular cross section is formed on the outersurface of main shaft portion 3116, whereby a spiral oil passage throughwhich oil flows is provided between main bearing 3114 and lead groove3151.

The upper end of lead groove 3151 communicates with eccentriccommunicating portion 3160 positioned within eccentric portion 3117.

The operation and action of the compressor having the above structureare now described.

When stator 3106 is energized by the inverter driving circuit, rotor3107 rotates with shaft 3111. The eccentric motion of eccentric portion3117 thus caused reciprocates piston 3113 within cylinder 3108 viaconnecting rod 3118, thereby carrying out predetermined compressingactions for taking in and compressing refrigerant 3103.

In accordance with the rotation of main shaft portion 3116 of shaft3111, oil 3102 rises through the oil passage formed between the outersurface of insertion member 3133 and the inner surface of sleeve 3131included in viscous pump 3130 while being pulled by the rotation ofsleeve 3131. Oil 3102 then passes through communicating hole 3140 andreaches the starting point of lead groove 3151. Subsequently, oil 7302further rises through the oil passage formed between lead groove 3151provided on the outer surface of main shaft portion 3116 of secondviscous pump 3150 and the inner surface of main bearing 3114 while beingpulled by the rotation of main shaft portion 3116. Finally, oil 3102 istransferred to eccentric portion 3117, connecting rod 3118 and othercomponents through eccentric communicating portion 3160.

In this embodiment as described above, most area of the oil passage ofmain shaft portion 3116 is occupied by viscous pump 3130 and secondviscous pump 3150 and the space for storing refrigerant 3103 and oil3102 is small. Therefore, oil 7302 is transferred to each sliding areaat high speed without decreasing the speed. Moreover, oil 3102 receivesnot only centrifugal force which decreases at the time of low-speedrevolution but also upward pressure while oil 3102 is being pulledwithin the oil passage due to viscosity, thereby drawing up oil 3102 ina reliable and stable manner even at the time of low-speed revolution.

Additionally, when oil 3102 in which refrigerant 3103 dissolves isheated by compressing element 3110, electrically-powered element 3105and other components and refrigerant 3103 is thus vaporized within theoil passage, the refrigerant gas is transferred together with oil 3102owing to the high oil-transfer performance of viscous pump 3130 andsecond viscous pump 3150 connected with each other without hinderingtransfer of oil 3102. As a result, oil 3102 can be transferred to eachsliding area at high speed immediately after start-up even at the timeof low-speed revolution such as 600 r/min., thereby realizing stable oiltransfer capability.

Accordingly, damages such as flaws and abrasion which may lead toexcessive wear or a locked condition of compressing element 3110 are notcaused when the sliding components contact each other.

In this embodiment, rotor 3107 is fitted to main shaft portion 3116 byshrinkage fitting or press fitting. However, since the inside diameterof cylindrical hollow portion 3135 alters at the time of attachment ofrotor 3107, the dimension of the space between cylindrical hollowportion 3135 and insertion member 3133 in the radial direction isdifficult to control. Thus, viscous pump 3130 is not provided in theregion where rotor 3107 is fitted to main shaft portion 3116. The lengthof that region, i.e., the length from the top surface of insertionmember 3133 to communicating hole 3140 is in a range from about 10 mm toabout 20 mm, which is substantially equivalent to the fitting length ofrotor 3107.

However, according to our finding from experiments in this embodiment, aknown parabolic free surface is produced on the upper surface of oil3102 within the cylindrical hollow portion due to centrifugal forceimmediately after start-up, and oil 3102 having reached the upper endsurface of insertion member 3133 instantly comes to communicating hole3140 as illustrated in FIG. 3. Thus, the oil transfer speed is scarcelyaffected if the length of the region where the pump is not provided isfrom about 10 mm to about 20 mm.

Since the oil transfer speed is considerably high, oil 3102 withincylindrical hollow portion 3135 rapidly flows into lead groove 3151immediately after start-up, causing negative pressure inside cylindricalhollow portion 3135. As a result, such a phenomenon that insertionmember 3133 is sucked toward the upper region of cylindrical hollowportion 3135 is caused in very few cases. Additionally, reaction forceagainst the force for moving oil upward caused by viscosity is alwaysapplied to insertion member 3133 in the downward direction duringcontinuous operation.

However, floating of insertion member 3133 in the vertical direction isrestricted by the engagement between the center portion of supportingmember 3132 and engagement holes 3137 of insertion member 3133. Thus,the structure of viscous pump 3130 in which oil 3102 is drawn up throughthe space between cylindrical hollow portion 3135 and insertion member3133 due to viscosity can be maintained both at the start-up and duringcontinuous driving.

Since the clearance between sleeve 3131 and insertion member 3133 ismaintained by the oil pressure generated within spiral groove 3134, thepossibility of sliding abrasion and fixation between sleeve 3131 andinsertion member 3133 is extremely low. Additionally, by determining thedifference between the inside diameter of engagement holes 3137 and theoutside diameter of supporting member 3132 in a range from severalhundred μm to 1 mm instead of completely fixing supporting member 3132to engagement holes 3137, the clearance between sleeve 3131 andinsertion member 3133 can be similarly maintained.

Joining portions 3138 of engagement holes 3137 are open in the advancingdirection of main shaft portion 3116, and a force in the rotationaldirection is applied on the side on which engagement holes 3137 areclosed even at the time of high-speed revolution at a driving frequencyin a range from 4,200 to 4,800 r/min., for example. However, this forceis scarcely applied on the side on which joining portions 3138 are open.In this structure, insertion member 3133, which does not rotate by therestriction of supporting member 3132, is prevented from coming off fromthe predetermined position even at the time of high-speed driving.

The length of the regions of joining portions 3138 which are open tonotches 3136 is smaller than the outside diameter of supporting member3132. Thus, supporting member 3132 does not easily come off fromengagement holes 3137 once it is inserted into engagement holes 3137,even if uncertain events such as vibrations occur during assembly at theline or transportation.

The compressor in this embodiment is inexpensive, as it does not requireadditional components for restricting rotation and vertically floatingof insertion member 3133.

Since a reliable and sufficient amount of oil 3102 is transferred evenat the time of low-speed revolution, it is possible to reduce heatgenerated from main shaft portion 3116, electrically-powered element3105 and other components and thus prevent temperature increase of oil3102. Accordingly, while R600a as isobutane is more soluble in oil 3102than R134a, vaporization of R600a and resultant accumulation of the gasdo not occur within the oil passage, thereby preventing generation ofobstruction for the transfer of oil 3102 such as a gas choke phenomenon.

Viscous pump 3130 and second viscous pump 3150 are assembled integrallywith electrically-powered element 3105 and compressing element 3110,inserted into closed container 3101, and finally supported withelasticity by springs 3104 inside closed container 3101. Thus,constituting components for viscous pump 3130 and second viscous pump3150 are not required to be provided in closed container 3101.Accordingly, the compressor in this embodiment is easily assembled andhas high productivity, and requires only the minimum number ofcomponents and thus realizes cost reduction in manufacture.

In this embodiment, sleeve 3131 is fastened within cylindrical hollowportion 3135. However, insertion member 3133 may be directly insertedinto cylindrical hollow portion 3135 formed by the processed main shaftportion to provide a viscous pump instead of using sleeve 3131, if theaccuracy within 500 μm can be secured for the clearance between theoutermost surface of insertion member 3133 and the inside surface ofcylindrical hollow portion 3135. While the number of components in thisstructure is different from that of the above-described embodiment, bothcases are basically identical in the aspects of operation, action andadvantages.

Embodiment 2

FIG. 4 is a cross-sectional view illustrating a main part of acompressor in a second embodiment of the invention, FIG. 5 is aperspective view of a lower part of a shaft in the second embodiment,and FIG. 6 is a cross-sectional enlarged view illustrating a sleeve inthe second embodiment.

The second embodiment is herein described with reference to FIGS. 4, 5and 6. Similar numbers are given to the structures similar to those ofthe first embodiment, and detailed description of those is omitted.

Main shaft portion 3216 of shaft 3211 included in compressing element3210 has viscous pump 3230 soaked with oil 3102 and second viscous pump3150 connected with viscous pump 3230 through communicating hole 3140.Second viscous pump 3150 is disposed above viscous pump 3230.

Next, the structures of viscous pump 3230 and second viscous pump 3150connected with each other are described in detail.

Viscous pump 3230 is coaxially inserted into cylindrical hollow portion3235 formed in main shaft portion 3216 and sleeve 3231 secured to thelower region of cylindrical hollow portion 3235. Viscous pump 3230includes insertion member 3233 having two supporting members 3232 whichextend from the lower end of insertion member 3233 in the almosthorizontal direction, and restricting means 339 having free joints 3261which is combined with supporting members 3232 such that free joints3261 and supporting members 3232 can freely rotate so as to restrictfloating of insertion member 3233.

The upper end of cylindrical hollow portion 3235 reaches the lower partof main bearing 3114.

Thread-shaped spiral groove 3234 is formed on the inner surface ofsleeve 3231 to provide a spiral oil passage between spiral groove 3234and insertion member 3233, through which passage oil 3102 is allowed toflow.

Insertion member 3233 has refrigerant-resistance and oil-resistanceproperties, and is made from plastic material or other material havinglower thermal conductivity than metal material. Supporting members 3232made from metal wire penetrate through the lower end of insertion member3233 to be fixed thereto.

Substantially L-shaped free joint 3261 is fixed to the lower part ofstator 3106 at one end, and has notch 3236 and engagement hole 3237 atthe other end. The end of supporting member 3232 which is formed at thelower end of insertion member 3233 is inserted through notche 3236 intoengagement hole 3237, thereby combining supporting member 3232 and freejoint 3261 such that both can freely rotate. This structure restrictsfloating of insertion member 3233 in the rotational and verticaldirections.

Notches 3236 are disposed before engagement holes 3237 in the advancingdirection of main shaft portion 3216 and joined with engagement holes3237. The length of joining portions 3238 of engagement holes 3237,i.e., the length of the openings in contact with notches 3236 is smallerthan the outside diameter of supporting members 3232.

Second viscous pump 3250 include main shaft portion 3216, lead groove3251 engraved on the outer surface of main shaft portion 3216, and mainbearing 3114.

Lead groove 3251 having a trapezoidal or substantially semicircularcross section is formed on the outer surface of main shaft portion 3216,whereby a spiral oil passage through which oil 3102 flows is providedbetween main bearing 3114 and lead groove 3251.

The operation and action of the compressor having the above structureare now described.

When stator 3106 is energized by the inverter driving circuit, mainshaft portion 3216 of shaft 3211 rotates. In accordance with thisrotation, oil 3102 rises through the oil passage formed between theinner surface of sleeve 3231 and the outer surface of insertion member3233 included in viscous pump 3230 while being pulled by the rotation ofsleeve 3231. Oil 3102 then passes through communicating hole 3140 andreaches the starting point of lead groove 3251.

Subsequently, oil 3102 further rises through the oil passage formedbetween lead groove 3251 provided on the outer surface of main shaftportion 3216 and the inner surface of main bearing 3114 included insecond viscous pump 3250 while being pulled by the rotation of mainshaft portion 3216.

In the embodiment as described above, oil 3102 is transferred to eachsliding area at high speed by the similar mechanism as in the firstembodiment. Moreover, the stable oil transfer capability can bemaintained even at the time of low-speed revolution such as 600 r/min.Accordingly, damages such as flaws and abrasion which may lead toexcessive wear or a locked condition of compressing element 3210 are notcaused when the sliding components contact each other, and thus a highlyreliable compressor can be provided.

Moment generated through the rotation applies load, and the load appliedto a certain position decreases as the distance from that position tothe rotational shaft center of shaft 3211 increases. Since the distancebetween the rotational shaft center and combining portion 3263 forcombining supporting member 3232 and free joint 3261 included inrestricting means 3239 is large in this embodiment, the load applied tocombining portions 3263 is decreased, thereby considerably reducing thepossibility of breaking of combining portions 3263.

In this embodiment, spiral groove 3234 is formed on the inner surface ofsleeve 3231 to enlarge the area of inner surface of the rotational bodyin contact with oil 3102 by adding the surface area of the concaves ofspiral groove 3234. This structure causes large viscous resistance,thereby enhancing oil transfer capability.

Furthermore, centrifugal force generated through the rotation of mainshaft portion 3216 is applied to oil 3102 existing within the oilpassage formed between the inner surface of sleeve 3231 and the outsidesurface of insertion member 3233 and oil 3102 rises while rotating andinclining toward the farthermost surface from the rotational shaftcenter in the oil passage. Since there is no clearance in the oilpassage to which the centrifugal force is most applied in thisembodiment, oil 3102 does not fall to flow out and thus the amount ofoil 3102 which falls to flow out can be controlled. Accordingly, thecompressor in this embodiment has considerably higher transfercapability of oil 3102 than the example in which the spiral groove isformed on insertion member 3233.

Embodiment 3

FIG. 7 is a cross-sectional view illustrating a main part of acompressor in a third embodiment of the invention, FIG. 8 is aperspective view of a lower part of a shaft in the third embodiment, andFIG. 9 is a cross-sectional enlarged view illustrating a sleeve in thethird embodiment.

The third embodiment is herein described with reference to FIGS. 7, 8and 9. Similar numbers are given to the structures similar to those ofthe first embodiment, and detailed description of those is omitted.

Main shaft portion 3316 of shaft 3311 included in compressing element3310 has viscous pump 3330 soaked with oil 3102 and second viscous pump3350 connected with viscous pump 3330 through communicating hole 3140.Second viscous pump 3150 is disposed above viscous pump 3330.

Next, the structures of viscous pump 3330 and second viscous pump 3350connected with each other are described in detail.

Viscous pump 3330 includes: cylindrical hollow portion 3335 formed inmain shaft portion 3316; sleeve 3331 secured to cylindrical hollowportion 3335; spiral member 3373 as a coil spring fixed to the innersurface of sleeve 3331; insertion member 3333 coaxially inserted intocylindrical hollow portion 3335 and sleeve 3331; and restricting means3339 having supporting member 3332 for restricting floating of insertionmember 3333.

Supporting member 3332 is substantially U-shaped and made from elasticmaterial such as iron spring wire. Both ends of supporting member 3332are fixed to the lower region of stator 3106. The center portion ofsupporting member 3332 engages with engagement grooves 3336 provided atthe lower end of insertion member 3333 to restrict floating of insertionmember 3333 in the rotational and vertical directions.

Eccentric passage 3372 formed above cylindrical hollow portion 3335 hasa smaller inside surface diameter than the inside diameter of sleeve3331, and is off-centered from the rotational shaft center toward theside where communicating hole 3140 is provided. The floating ofinsertion member 3333 in the upward direction is restricted bycontacting with upper bottom 3380 of cylindrical hollow portion 3335.The clearance between the upper surface of insertion member 3333 andupper bottom 3380 of cylindrical hollow portion 3335 is so determined asto be smaller than a height (B) of engagement groove 3336 in thelongitudinal direction so as to prevent separation of insertion member3333 from supporting member 3332 when insertion member 3333 rises.

The upper end of eccentric passage 3372 reaches the lower part of mainbearing 3114, where eccentric passage 3372 communicates withcommunicating hole 3140.

An oil passage is formed between spiral member 3373 as the coil springfixed to the inner surface of sleeve 3331 and insertion member 3333,through which passage oil 3102 is allowed to flow.

Substantially cylindrical sleeve 3331 has a shape of a cap whose top andbottom are open. Sleeve 3331 has substantially L-shaped spring holder3374 at its lower region. Sleeve 3331 is made from iron plate pressmaterial which can be processed with relatively high accuracy in thisembodiment, but may be made from leaf spring steel.

The length of the coil spring of spiral member 3373 is larger than thetotal length of the inner surface of sleeve 3331 from which the lengthof the spring holder 3374 in the axial direction is subtracted. As aresult, spiral member 3373 is compressed between upper bottom 3380 ofcylindrical hollow portion 3335 and spring holder 3374 and fixed to theinner surface of sleeve 3331.

Spiral member 3373 is made from oil temper wire for springs (SWOV) inthis embodiment, but may be made from other material including ironsteel such as piano wire (SWP) and spring steel (SUP), non-iron metalsuch as aluminum, plastic material (PC, PA) whose thermal deformationtemperature is 100° C. or higher and which has high formability, andother material having oil transfer capability of the spiral groove.

Second viscous pump 3350 includes main shaft portion 3316, lead groove3351 engraved on the outer surface of main shaft portion 3316, and mainbearing 3114.

Lead groove 3351 having a trapezoidal or substantially semicircularcross section is formed on the outer surface of main shaft portion 3316,whereby a spiral oil passage through which oil 3102 flows is providedbetween main bearing 3114 and lead groove 3351.

The operation and action of the compressor having the above structureare now described.

When stator 3106 is energized by the inverter driving circuit, mainshaft portion 3316 of shaft 3311 rotates. In accordance with thisrotation, oil 3102 rises through the oil passage formed between spiralmember 3373 and the outer surface of insertion member 3333 included inviscous pump 3330 while being pulled by the rotation of sleeve 3331. Oil3102 then passes through communicating hole 3140 and reaches thestarting point of lead groove 3351.

Subsequently, oil 3102 further rises through the oil passage formedbetween lead groove 3351 and the inner surface of main bearing 3114included in second viscous pump 3350 while being pulled by the rotationof main shaft portion 3116.

In the embodiment as described above, oil is transferred to each slidingarea at high speed by the similar mechanism as in the first embodiment.Moreover, the stable oil transfer capability can be maintained even atthe time of low-speed revolution such as 600 r/min. Accordingly, damagessuch as flaws and abrasion which may lead to excessive wear or a lockedcondition of compressing element 3310 are not caused when the slidingcomponents contact each other, and thus a highly reliable compressor canbe provided.

In assembly, the position of insertion member 3333 within cylindricalhollow portion 3335 in the vertical direction can be determined byaligning the upper surface of insertion member 3333 with upper bottom3380 of cylindrical hollow portion 3335. Supporting member 3332 can beattached to insertion member 3333 by bringing supporting member 3332into engagement with engagement grooves 3336 provided at the lower endof insertion member 3333. Thus, the assembly is facilitated.

In this embodiment, viscous pump 3330 which uses the shape of the coilspring itself as spiral member 3373 provided on the inner surface ofsleeve 3331 can be far more easily formed than the structure in which aspiral groove is directly engraved on the inner surface of sleeve 3331.

From the viewpoint of energy saving, the amount of oil transfer can beappropriately controlled by replacing the coil spring with the onehaving a different wire diameter, wire cross-sectional shape, number ofwinding etc., in accordance with the driving frequency required by thesystem side such as household refrigerators and air conditioners. Thus,the compressor of this embodiment is highly flexible and capable ofmeeting a wide variety of demands.

Attachment of sleeve 3331 to the lower end of main shaft portion 3316 iscompleted by forcedly inserting sleeve 3331, which has the coil springof spiral member 3373 around its inner surface in advance, intocylindrical hollow portion 3335 formed coaxially with main shaft portion3316. Also, formation of the spiral groove necessary for the upwardtransfer of oil 3102 is completed by compressing spiral member 3373between upper bottom 3380 of cylindrical hollow portion 3335 and springholder 3374 and securing spiral member 3373 to the inner surface ofsleeve 3331.

Thus, the assembly is extremely practical and easy, thereby enhancingproductivity.

In the invention as described above, since most area of the oil passageof the main shaft portion is occupied by the pumps, the space forstoring oil and refrigerant is small and oil is transferred at highspeed. Also, not only centrifugal force which decreases at the time oflow-speed revolution but also upward pressure is given to oil while oilis being pulled within the passage due to viscosity, thereby drawing upoil in a reliable and stable manner even at the time of low-speedrevolution. Therefore, a highly reliable compressor having positive andstable oil transfer capability can be provided.

In addition to the above advantage, the highly reliable compressorprovided according to the invention has high productivity and ismanufactured at low cost.

Another advantage of the highly reliable compressor provided accordingto the invention is that the rotation, rising and falling of theinsertion member can be securely prevented even at the start-up andduring continuous driving, thereby realizing reliable and stable oiltransfer capability.

Another advantage of the highly reliable compressor provided accordingto the invention is that rising and resultant separation of theinsertion member from the restricting means and also abrasion andchipping of the insertion member due to the contact and collisionbetween the inner surface of the cylindrical hollow portion and theouter surface of the insertion member are prevented, thereby realizingreliable and stable oil transfer capability.

Another advantage of the highly reliable compressor provided accordingto the invention is that the possibility of breaking of the restrictingmeans is extremely low.

Another advantage of the highly reliable compressor provided accordingto the invention is that assembly of the compressor is facilitated.

Another advantage of the highly reliable compressor provided accordingto the invention is that multiplicatively large oil transfer capabilitycan be obtained.

Another advantage of the highly reliable compressor provided accordingto the invention is that the compressor is highly flexible and hasenhanced productivity.

Another advantage of the highly reliable compressor provided accordingto the invention is that power consumption is reduced since input to thecompressor is decreased and oil supply is stabilized.

Another advantage of the highly reliable compressor provided accordingto the invention is that the compressor is easily assembled to achieveenhanced productivity and includes the viscous pumps.

Another advantage of the highly reliable compressor provided accordingto the invention is that generation of obstructions to the oil transfersuch as gas choke phenomenon is prevented.

Another advantage of the highly reliable compressor provided accordingto the invention is that the compressor gives extremely little adverseeffect on the global environment since the greenhouse effect coefficientof R600a employed is substantially zero and low-speed revolution reducespower consumption.

In the above-described conventional structure in which bracket 7115supports insertion member 7120, insertion member 7120 comes to be fixedwithin sleeve 7112 if the dimensional precision is insufficient. Thisfixation is absorbed by the elasticity of the material of bracket 7115.However, if the fixation is extremely large, abrasion is generatedbetween sleeve 7112 and insertion member 7120. The abrasion thus causedmay decrease the pumping ability and generate abrasion powder which iscirculated with oil toward the sliding area and caught between thesliding components and thus brings about a locked condition of thecompressing element.

Additionally, as insertion member 7120 passes through rotor 7107 to beindirectly fixed to stator 7106, additional long components forinsertion member 7120 with stator 7106 and suitable means and processesfor fixing those components are required. Thus, the cost of thecompressor is inevitably raised. It is thus an object of the inventionto provide a highly reliable and inexpensive compressor.

Compressors in Fourth and fifth embodiments of the present invention areherein described with reference to the drawings.

Embodiment 4

FIG. 10 is a cross-sectional view illustrating a compressor in thefourth embodiment of the invention, FIG. 11 is a cross-sectional viewillustrating a main part of the compressor in the fourth embodiment, andFIG. 12 is a perspective view illustrating the main part of thecompressor in the fourth embodiment.

In FIGS. 10 to 12, oil 1102 is stored in closed container 1101 which isfilled with refrigerant gas 1103.

Compressing element 1110 includes: block 1115 which forms cylinder 1113;piston 1117 reciprocatively inserted into cylinder 1113; shaft 1125having main shaft portion 1120 supported by main bearing 1116 of block1115 and eccentric portion 1122; and connecting rod 1119 for connectingeccentric portion 1122 and piston 1117. Compressing element 1110 forms areciprocating compressing mechanism.

Electrically-powered element 1135 is fixed below block 1115.Electrically-powered element 1135 includes stator 1136 connected to aninverter driving circuit (not shown) and rotor 1137 which containspermanent magnet and is fixed to main shaft portion 1120.Electrically-powered element 1135 thus forms an electrically-poweredelement for driving the inverter.

Springs 1139 elastically support compressing element 1110 via stator1136 so that compressing element 1110 can be elastically supported onclosed container 1101.

Main shaft portion 1120 of shaft 1125 has viscous pump 1140 soaked withoil 1102 at its lower end. Viscous pump 1140 includes: cylindricalhollow portion 1142 formed in the lower region of main shaft portion1120; insertion member 1145 coaxially and rotatably inserted intocylindrical hollow portion 1142; and impellers 147 having a plurality ofvanes which are formed integrally with insertion member 1145. Athread-shaped spiral projection 1149 is provided on the outer surface ofinsertion member 1145, thereby forming a spiral groove 1150 throughwhich oil 1102 flows between spiral projection 1149 and cylindricalhollow portion 1142.

Insertion member 1145 and impellers 1147 have component 1151 formed by ashaped plastic component having refrigerant-resistance andoil-resistance properties. Component 1151 is hollow and has upper region1152 where penetration 1153 is opened. Screw 1157 inserted intopenetration 1153 rotatably connects component 1151 to the ceiling ofcylindrical hollow portion 1142.

Communicating hole 1160 extends upward from the ceiling of cylindricalhollow portion 1142 to connect cylindrical hollow portion 1142 withlateral hole 1162 which is open to a sliding area formed by the innersurface of bearing 1116 and the outer surface of main shaft portion1120.

The operation of the compressor having the above structure is nowdescribed. When stator 1136 is energized by the inverter drivingcircuit, rotor 1137 rotates with shaft 1125. In accordance with thisrotation, the eccentric motion of eccentric portion 1122 reciprocatespiston 1117 within cylinder 1113 via connecting rod 1119, therebycarrying out predetermined actions for compressing gas which is takenin.

Cylindrical hollow portion 1142 rotates with the rotation of main shaftportion 1120 of shaft 1125. Insertion member 1145 then tries to rotatewith the rotation of cylindrical hollow portion 1142, but in realityinsertion member 1145 rotates at a number of revolution far smaller thanthat of cylindrical hollow portion 1142 since impellers 1147 receivestrong viscous resistance in the rotational direction within oil 1102.Thus, there is a difference in the number of revolution betweencylindrical hollow portion 1142 and insertion member 1145, whichdifference is near the number of revolution of shaft 1125. Consequently,oil 1102 rises within spiral groove 1150 while being pulled by therotation of cylindrical hollow portion 1142. Then, oil 1102 furtherrises through communicating hole 1160 by the oil pressure thusgenerated, passes through lateral hole 1162, and reaches the slidingarea formed by the inner surface of bearing 1116 and the outer surfaceof main shaft portion 1120 to lubricate that area.

At this stage, oil 1102 rises while rotating not only by the centrifugalforce which decreases at low-speed revolution but by a pulling forcegenerated by viscosity. Thus, oil can be drawn up in a stable mannereven at the time of low-speed revolution such as 600 rpm.

According to this embodiment, since component 1151 is rotatablyconnected to the ceiling of cylindrical hollow portion 1142 only byscrew 157 inserted into penetration 1153, lateral pressure due tofixation is scarcely applied between cylindrical hollow portion 1142 andinsertion member 1145, and there is very few possibility of occurrenceof sliding abrasion between cylindrical hollow portion 1142 andinsertion member 1145. It is thus possible to prevent generation ofabrasion powder which is circulated with oil toward the sliding area andcaught between the sliding components and thus brings about a lockedcondition of the compressing element. Accordingly, the compressorprovided according to this embodiment is highly reliable.

Furthermore, the rotation of insertion member 1145 is prevented whileimpellers 1147 are receiving strong viscous resistance in the rotationaldirection within oil 1102. Thus, indirect fixing of insertion member1145 to stator 1136 as in the conventional example is not needed. Also,since the structure is extremely simple in which insertion member 1145is rotatably connected to the ceiling of cylindrical hollow portion 1142only by screw 1157 inserted into penetration 1153 of upper region 1152,only a small number of components and processes are required andcost-reduction of the compressor is attained.

Embodiment 5

FIG. 13 is a cross-sectional view illustrating a main part of acompressor in a fifth embodiment according to the invention. The fifthembodiment is herein described with reference to FIG. 13. Similarnumbers are given to the structures similar to those of the fourthembodiment, and detailed description of those is omitted.

Viscous pump 1240 soaked with oil 1102 is provided at the lower end ofmain shaft portion 1220 of shaft 1225.

Communicating hole 1241 is coaxially formed within main shaft portion1220. Viscous pump 1240 includes: sleeve 1243 forcedly inserted intocommunicating hole 1241 and fixed thereto to form cylindrical hollowportion 1242; insertion member 1246 coaxially and rotatably insertedinto sleeve 1243; and impellers 1247 having a plurality of vanes whichare formed integrally with insertion member 1246.

Sleeve 1243 is substantially cylindrical and cap-shaped, and has uppersurface 1245 where screw hole 1244 is provided. Upper surface 1245 haspath hole 1248 through which oil 1102 flows.

Sleeve 1243 is made from iron plate press material which offerscomparatively high accuracy and is an appropriate material through whichinsertion member 1246 slides, but may be formed from other suitablematerials through which insertion member 1246 slides such as plasticsand leaf spring steel.

A thread-shaped spiral projection 1249 is provided on the outer surfaceof insertion member 1246, thereby forming spiral groove 1250 throughwhich oil 1102 flows between spiral projection 1249 and sleeve 1243.

Insertion member 1246 and impellers 1247 have component 1251 formed by ashaped plastic component having refrigerant-resistance andoil-resistance properties. Component 1251 is hollow and has upper region1252 where penetration 1253 is provided. Screw 1257 inserted throughpenetration 1253 is screwed into screw hole 1244 via washer 1257 a torotatably connect component 1251 to upper surface 1245.

Washer 1257 a is made from 4-fluorinated ethylene and controls thesliding with component 1251 in the thrust direction.

Communicating hole 1241 opens to a sliding area formed by the innersurface of bearing 1116 and the outer surface of main shaft portion 1220to communicate with the sliding area through lateral hole 1262.

The operation of the compressor having the above structure is nowdescribed.

When stator 1136 is energized by the inverter driving circuit, rotor1137 rotates with shaft 1225.

In accordance with the rotation of main shaft portion 1220 of shaft1225, cylindrical hollow portion 1242 formed by sleeve 1243 rotates.Insertion member 1246 then tries to rotate with the rotation ofcylindrical hollow portion 1242, but in reality insertion member 1246rotates at a number of revolution far smaller than that of cylindricalhollow portion 1242 since impellers 1247 receive strong viscousresistance in the rotational direction within oil 1102. Thus, there is adifference in the number of revolution between cylindrical hollowportion 1242 and insertion member 1246, which difference is near thenumber of revolution of shaft 1225. Consequently, oil rises throughspiral groove 1250 while being pulled by the rotation of cylindricalhollow portion 1242. Then, oil 1102 further rises through path hole 1248in communicating hole 1241 by the oil pressure thus caused, passesthrough lateral hole 1262, and reaches the sliding area formed by theinner surface of bearing 1116 and the outer surface of main shaftportion 1220 to lubricate that area.

At this stage, oil 1102 rises while rotating not only by the centrifugalforce which decreases at low-speed revolution but by a pulling forcegenerated by viscosity. Thus, oil can be drawn up in a stable mannereven at the time of low-speed revolution such as 600 rpm.

According to this embodiment, component 1251 is rotatably connected toupper surface 1245 via washer 1257 a only by screw 1257 inserted throughpenetration 1253. Thus, lateral pressure due to fixation is scarcelyapplied between sleeve 1243 and insertion member 1246, and there is veryfew possibility of occurrence of sliding abrasion between sleeve 1243and insertion member 1246. It is thus possible to prevent generation ofabrasion powder which is circulated with oil and caught between thesliding components and thus brings about a locked condition of thecompressing element. Accordingly, the compressor provided according tothis embodiment is highly reliable.

A force in the downward direction as a reaction to a force for pushingup oil 1102 is applied to sleeve 1243. The downward force is given tothe sliding surface as a load in the thrust direction. The sliding areaexists at the position between upper surface 1245 of sleeve 1243 andwasher 1257 a in this embodiment, but extreme abrasion at that positionis prevented by the self-lubrication ability of washer 1257 a which ismade from 4-fluorinated ethylene.

The rotation of insertion member 1246 is prevented while impellers 1247are receiving strong viscous resistance in the rotational directionwithin oil 1102. Thus, indirect fixing of insertion member 1246 tostator 1136 as in the conventional example is not needed. Also, sincethe structure is extremely simple in which insertion member 1246 isrotatably connected to upper surface 1245 via washer 1257 a only byscrew 1257 inserted through penetration 1253 of upper region 1252, onlya small number of components and processes are required and thuscost-reduction of the compressor can be attained.

In this embodiment, viscous pump 1240 is assembled in advance as anindependent component by joining sleeve 1243 and component 1251 by screw1257 inserted via washer 1257 a. After rotor 1137 is forcedly fitted toshaft 1225, viscous pump 1240 as the independent component is forcedlyfitted to communicating hole 1241 to complete the assembly. Thus,drastically practical and enhanced productivity can be attained.

Embodiment 6

FIG. 14 is a cross-sectional view illustrating a main part of acompressor in a sixth embodiment according to the present invention. Thesixth embodiment is herein described with reference to FIG. 14. Similarnumbers are given to the structures similar to those of the fourthembodiment, and detailed description of those is omitted.

Viscous pump 1340 soaked with oil 1102 is provided at the lower end ofmain shaft portion 1320 of shaft 1325.

Communicating hole 1341 is coaxially formed within main shaft portion1320. Viscous pump 1340 includes: sleeve 1343 forcedly inserted intocommunicating hole 1341 and fixed thereto to form cylindrical hollowportion 1342; insertion member 1346 coaxially and rotatably insertedinto sleeve 1343; and impellers 1347 having a plurality of vanes whichare formed separately from insertion member 1346.

Sleeve 1343 is substantially cylindrical and cap-shaped, and has bottomsurface 1345 where rod hole 1344 is formed at its center. Bottom surface1345 has path hole 1348 through which oil 1102 flows. Sleeve 1343 ismade from iron plate press material which offers comparatively highaccuracy and is an appropriate material through which insertion member1336 slides, but may be formed from other suitable materials throughwhich insertion member 1336 slides such as plastics and leaf springsteel.

Insertion member 1346 is formed by a shaped plastic component havingrefrigerant-resistance and oil-resistance properties and hasthread-shaped spiral projection 1349 on its outer surface, therebyforming spiral groove 1350 through which oil 1102 flows between spiralprojection 1349 and sleeve 1343. Bottom region 1352 has a small-diameterhole 1353.

In this embodiment, impellers 1347 are stamped out from thin iron plate,and rod 1349 made from steel wire which is resistance-welded toimpellers 1347 is forcedly inserted through rod hole 1344 intosmall-diameter hole 1353 formed on bottom region 1352 to be fixedthereto. Communicating hole 1341 opens to a sliding area formed by theinner surface of bearing 1116 and the outer surface of main shaftportion 1320 through lateral hole 1362 to communicate with the slidingarea.

The operation of the compressor having the above structure is nowdescribed. When stator 1136 is energized by the inverter drivingcircuit, rotor 1137 rotates with shaft 1325. In accordance with therotation of main shaft portion 1320 of shaft 1325, cylindrical hollowportion 1342 formed by sleeve 1343 rotates. Insertion member 1346 triesto rotate with the rotation of cylindrical hollow portion 1342, but inreality insertion member 1346 rotates at a number of revolution farsmaller than that of cylindrical hollow portion 1342 since impellers1347 receive strong viscous resistance in the rotational directionwithin oil 1102. Thus, there is a difference in the number of revolutionbetween cylindrical hollow portion 1342 and insertion member 1346, whichdifference is near the number of revolution of shaft 1325. Consequently,the oil having entered through path hole 1348 rises through spiralgroove 1350 while being pulled by the rotation of cylindrical hollowportion 1342. Then, the oil further rises through communicating hole1341 by the oil pressure thus generated, passes through lateral hole1362, and reaches the sliding area formed by the inner surface ofbearing 1116 and the outer surface of main shaft portion 1320 tolubricate that area.

At this stage, oil 1102 rises while rotating not only by the centrifugalforce which decreases at low-speed revolution but by a pulling forcegenerated by viscosity. Thus, oil can be drawn up in a stable mannereven at the time of low-speed revolution such as 600 rpm.

According to this embodiment, insertion member 1346 and sleeve 1343provide a thrust sliding area formed by bottom region 1352 and bottomsurface 1345 which rotatably contact with each other. Thus, lateralpressure due to fixation is scarcely applied between sleeve 1343 andinsertion member 1346, and there is very few possibility of occurrenceof sliding abrasion between sleeve 1343 and insertion member 1346. It isthus possible to prevent generation of abrasion powder which iscirculated with oil toward the sliding area and caught between thesliding components and thus brings about a locked condition of thecompressing element. Accordingly, the compressor provided according tothis embodiment is highly reliable.

A force in the downward direction as a reaction to a force for pushingup oil 1102 is applied to sleeve 1343. The downward force is given tothe thrust sliding area forming by above mentioned bottom region 1352and bottom surface 1345 as a load in the thrust direction. In thisembodiment, the surface pressure applied to the thrust sliding area canbe reduced by widening bottom surface 1345 of sleeve 1343, therebyimproving abrasion resistance.

While not shown in the above respective embodiments, a spacer havingabrasion resistance such as 4-fluorinated ethylene and valve steel maybe interposed between bottom region 1352 and bottom surface 1345 tofurther enhance abrasion resistance.

The rotation of insertion member 1346 is prevented while impellers 1347are receiving strong viscous resistance in the rotational directionwithin oil 1102. Thus, indirect fixing of insertion member 1346 tostator 1136 by a component for preventing the rotation of insertionmember 1346 as in the conventional example is not needed. Also, sincethe structure is extremely simple, only a small number of components andprocesses are required and thus cost-reduction of the compressor can beattained.

According to the above respective embodiments, viscous pump 1340 isassembled in advance as an independent component by inserting insertionmember 1346 into sleeve 1343 and forcedly inserting rod 1349 to whichimpellers 1347 are fixed through rod hole 1344 into small-diameter hole1353 formed on bottom region 1352. After rotor 1137 is forcedly insertedinto shaft 1325, viscous pump 1340 as the independent component isforcedly inserted into communicating hole 1341 to complete the assembly.Thus, drastically practical and enhanced productivity can be attained.

While the spiral projection is provided on the insertion member in thefourth through sixth embodiments, the spiral projection may be disposedon the cylindrical hollow portion to similarly form the spiral groovethrough which oil flows.

While description is made based on the reciprocating internalsuspended-type compressor in the fourth through sixth embodiments, thepresent invention is applicable to internal fixed-type compressors suchas vertical rotary-type compressors and scroll-type compressors as longas the lower end of their shafts extends to reach oil.

Types of gas and oil are not specifically limited. Needless to say, theadvantages of the invention can be generally offered in any combinationof all types of refrigerant involving environment-protective refrigerantsuch as HFC, HC and CO2 and all types of oil involving oil compatiblewith those refrigerant by employing the above materials havinggas-resistance and oil-resistance properties for the components includedin the viscous pump.

According to the invention as described above, a component for fixingthe insertion member to the stator is not required, and thus a highlyreliable and inexpensive compressor can be provided.

Another advantage offered according to the invention is that a materialhaving high abrasion resistance can be used to further enhancereliability.

Another advantage offered according to the invention is that the viscouspump is assembled into one piece in advance, and thus a furtherinexpensive compressor can be provided.

Another advantage offered according to the invention is that the viscouspump assembled into one piece in advance, and thus a further inexpensivecompressor can be provided.

Another advantage offered according to the invention is that the viscouspump is incorporated in the compressor which is elastically supported,and thus a highly reliable and inexpensive compressor can be provided.

Another advantage offered according to the invention is that thecompressor is driven at a low-speed revolution, and thus a highlyreliable and inexpensive compressor can be provided.

The force for pulling oil due to viscosity increases as the contact areabetween the inner surface of the rotational body and oil increases.However, the contact surface is chiefly formed by the flat smoothsurface of sleeve 7112 and only insufficient force is applied to oil inthe structure of the conventional example.

Additionally, there is a clearance between the end surface of spiralprojection 7121 and the inner surface of sleeve 7112, which clearance ispositioned at the outermost surface of insertion member 7120 in theconventional structure. The centrifugal force generated through therotation of shaft 7111 is applied to oil within the oil passage formedby the spiral groove and the inner surface of sleeve 7112, and oil riseswhile rotating and inclining toward the inside surface. Thus, oil fallsto flow out through the clearance between spiral projection 7121 andinner surface of sleeve 7112 and the oil supply amount to the upper areadecreases.

Accordingly, especially in an extremely low driving frequency range suchas 600 to 1,200 r/min., the force for pulling oil due to viscositydecreases and also the amount of oil which falls to flow out through theclearance between sleeve 7112 and insertion member 7120 increases. Inthis case, a sufficient oil amount cannot be transferred to the slidingarea positioned above.

It is therefore an object of the present invention to provide acompressor capable of drawing up a sufficient amount of oil withefficiency even at the time of low-speed revolution.

Compressors in seventh and eighth embodiments are herein described withreference to the drawings.

Embodiment 7

FIG. 15 is a cross-sectional view of a compressor in the seventhembodiment of the invention; FIG. 16 is across-sectional viewillustrating a main part of the compressor in the seventh embodiment.

In FIGS. 15 and 16, oil 2102 is stored in closed container 2101 which isfilled with refrigerant gas 2103.

Compressing element 2110 includes: block 2115 which forms cylinder 2113;piston 2117 reciprocatively inserted into cylinder 2113; shaft 2125having main shaft portion 2120 supported by bearing 2116 of block 2115and eccentric portion 2122; and connecting rod 2119 for connectingeccentric portion 2122 and piston 2117. Compressing element 2110 forms areciprocating compressing mechanism.

Electrically-powered element 2135 is fixed below block 2115.Electrically-powered element 2135 includes stator 2136 connected to aninverter driving circuit (not shown) and rotor 2137 which containspermanent magnet and is fixed to main shaft portion 2120, thus providingan electrically-powered element for driving the inverter.

Springs 2139 elastically support compressing element 2110 via stator2136 such that compressing element 2110 can be elastically held onclosed container 2101.

Viscous pump 2140 soaked with oil 2102 is provided at the lower end ofmain shaft portion 2120 of shaft 2125. Viscous pump 2140 includes:cylindrical hollow portion 2142 formed in the lower region of main shaftportion 2120; insertion member 2145 coaxially inserted into cylindricalhollow portion 2142; and substantially-U-shaped bracket 2143 both endsof which are fixed to the lower region of stator 2136. Bracket 2143engages with the lower end of insertion member 2145 to support insertionmember 2145 such that insertion member 2145 cannot rotate.

Thread-shaped spiral projection 2149 is formed on the inner surface ofcylindrical hollow portion 2142 to provide a spiral groove through whichoil 2102 is allowed to flow between spiral projection 2149 and insertionmember 2145.

Insertion member 2145 is hollow and a shaped component made from resinhaving refrigerant-resistance and oil-resistance properties. Insertionmember 2145 has bracket insertion portion 2146 and rise preventionmember 2147. Insertion member 2145 floats inside the cylindrical hollowportion, but is prevented from rising too high and rotating therein.

The operation of the compressor having the above structure is nowdescribed. When stator 2136 is energized by the inverter drivingcircuit, rotor 2137 rotates with shaft 2125. The eccentric motion ofeccentric portion 2122 thus caused reciprocates piston 2117 withincylinder 2113 via connecting rod 2119, thereby carrying outpredetermined actions for compressing gas which is taken in.

In accordance with the rotation of main shaft portion 2120 of shaft2125, cylindrical hollow portion 2142 rotates. Insertion member 2145engages with the center portion of substantially U-shaped bracket 2143both ends of which are fixed to the lower region of stator 2136 to besupported by bracket 2143 in such a manner as not to rotate. In thisstructure, oil rises through the spiral groove while being pulled by therotation of cylindrical hollow portion 2142. Then, oil further risesthrough communicating hole 2160 by the oil pressure thus caused, passesthrough lateral hole 2162, and finally reaches a sliding area formed bythe inner surface of bearing 2116 and the outer surface of main shaftportion 2120 to lubricate that area.

At this stage, oil 2102 rises while rotating not only by the centrifugalforce which decreases at low-speed revolution but by a pulling forcegenerated by viscosity. In addition, spiral projection 2149 is formed onthe cylindrical hollow portion to enlarge the area of the inner surfaceof the rotational body in contact with oil by adding the surface area ofspiral projection 2149 in this embodiment. This structure causes largeviscous resistance, thereby enhancing oil transfer capability.

Furthermore, centrifugal force generated by the rotation of shaft 2120is applied to oil existing in the space between the spiral groove formedon the inner surface of cylindrical hollow portion 2142 and insertionmember 2145. Thus, oil rises while rotating and inclining toward theroots of the spiral groove, i.e., the farthermost surface from therotational shaft center of shaft 2120. Structurally there is noclearance in the vicinity of the roots of the spiral groove to which thecentrifugal force is applied. Accordingly, oil does not fall to flowout, thereby preventing fall and outflow of oil.

As described above, enhanced oil transfer capability can be realized,allowing drawing up oil in a stable manner even at the time of low-speedrevolution such as 600 r/min.

According to this embodiment, the compressing element is elasticallysupported, and insertion member 2145 engages with the center of bracket2143 made from an elastic body to float within cylindrical hollowportion 2142 without rotating. Thus, lateral pressure due to fixation isscarcely applied between cylindrical hollow portion 2142 and insertionmember 2145, and there is very few possibility of occurrence of slidingabrasion between cylindrical hollow portion 2142 and insertion member2145. It is thus possible to prevent generation of abrasion powder whichis circulated with oil toward the sliding area and caught between thesliding components and thus brings about a locked condition of thecompressing element. Accordingly, the compressor provided according tothis embodiment is highly reliable.

Embodiment 8

FIG. 17 is a cross-sectional view illustrating a main part of acompressor in an eighth embodiment of the invention; and FIG. 18 is anassembly view of the main part in the eighth embodiment. The eighthembodiment is herein described with reference to FIGS. 17 and 18.Similar numbers are given to the structures similar to those of theseventh embodiment, and detailed description of those is omitted.

Viscous pump 2240 soaked with oil 2102 is provided at the lower end ofmain shaft portion 2220 of shaft 2225.

Communicating hole 2260 and sleeve attachment hole 2254 are coaxiallyformed within main shaft portion 2220. Viscous pump 2240 includes:sleeve 2251 which is forcedly inserted into sleeve attachment hole 2254to be fixed thereto and forms cylindrical hollow portion 2242; coilspring 2253 secured to the inner surface of sleeve 2251 as a spiralmember; insertion member 2145 coaxially and rotatably inserted intosleeve 2251; and bracket 2143. Bracket 2143 which is made from anelastic body is substantially U-shaped, both ends of which are fixed tothe lower region of stator 2136. The center of bracket 2143 engages withthe lower end of insertion member 2145 to support insertion member 2145in such a manner that insertion member cannot rotate.

Sleeve 2251 is substantially cylindrical and cap-shaped, whose top andbottom are open. Sleeve 2251 has spring holder 2252 at its lower end.Sleeve 2251 is made from iron plate press material which offerscomparatively high accuracy, but may be formed from other materials suchas leaf spring steel.

The length of coil spring 2253 is larger than the total length of theinner surface of sleeve 2251 from which the height of the spring holder2252 is subtracted. Coil spring 2253 is made from oil temper wire forsprings (JIS:SWOV) in this embodiment, but may be made from othermaterial including iron steel such as piano wire (JIS:SWP) and springsteel (JIS:SUP), non-iron metal such as aluminum, and resins whosethermal deformation temperature is 100° C. or higher and which has highformability such as polycarbonate (PC) and polyamide (PA).

Cylindrical hole 2255 formed by the lowermost end surface of main shaftportion 2220 has one step to provide a smaller-diameter hole. Sleeveattachment hole 2254 in to which a predetermined length of sleeve 2251is forcedly inserted is formed in a hole on the first step, whilecommunicating hole 2260 is formed in a hole on the second step. Theinner surface diameter of communicating hole 2260 is slightly smallerthan the inner surface diameter of sleeve 225 i. Coil spring 2253 iscompressed between spring holder 2252 at the lower end of the sleeve andthe step formed by the difference in the inner surface diameter betweensleeve 2251 and communicating hole 2260 to be fixed to the inner surfaceof sleeve 2251.

Insertion member 2145 is formed by a shaped resin component havingrefrigerant-resistance and oil-resistance properties in this embodiment,but may be comparatively light metal such as aluminum. Insertion member2145 is a hollow component, and has bracket insertion portion 2146 andrise prevention member 2147. Insertion member 2145 floats inside thecylindrical hollow portion, but is prevented from rising too high androtating therein.

The operation of the compressor having the above structure is nowdescribed.

When stator 2136 is energized by the inverter driving circuit, rotor2137 rotates with shaft 2125. Then, operations similar to those in theseventh embodiment are performed to supply oil.

According to this embodiment, the structure which uses the shape of thecoil spring itself as the spiral groove provided on the inner surface ofthe lower end of the shaft can be far more easily formed than thestructure in which a spiral groove is directly engraved on the innersurface of the lower end of the shaft. From the viewpoint of energysaving, the amount of oil transfer can be appropriately controlled byreplacing the coil spring with the one having a different wire diameter,wire cross-sectional shape, number of winding etc., in accordance withthe driving frequency required by the system side such as householdrefrigerators and air conditioners. Thus, the compressor of thisembodiment is highly flexible and capable of meeting a wide variety ofdemands. Moreover, by forcedly inserting sleeve 2251 provided with coilspring 2253 on its inner surface in advance into sleeve attachment hole2254 formed coaxially with main shaft portion 2220, sleeve 2251 isattached to the lower end region of main shaft portion 2220 andsimultaneously coil spring 2253 is compressed between spring holder 2252at the lower end of the sleeve and the step formed by the difference inthe inner surface diameter between sleeve 2251 and communicating hole2260 to be fixed to the inner surface of sleeve 2251. Accordingly, theformation of the spiral groove necessary for transferring oil upward iseasily completed, and thus considerably practical and high productivitycan be achieved.

According to the present invention as described above, it is possible tosecure a wide area in contact with oil which causes viscous resistanceneeded for the rotational rising movement of oil. Accordingly, the forcefor pulling oil due to viscosity increases and thus an enhanced oiltransfer capability can be obtained.

Another advantage of the invention is that the assembly in thisembodiment which uses the shape of the coil spring itself as the spiralgroove is more facilitated than in an example in which a groove isengraved. Also, the amount of oil transfer can be appropriatelycontrolled by replacing the coil spring with the one having a differentwire diameter, wire cross-sectional shape, number of winding etc., whichenhances the flexibility. Further, the spiral groove formed by the coilspring is simultaneously provided when the sleeve is forcedly inserted,which increases the productivity.

Another advantage of the invention is that power consumption ofhousehold refrigerators and air-conditioners is reduced since input tothe compressor is decreased during low-speed driving and oil supply isstabilized.

Another advantage of the invention is that the insertion member floatsbut not rotates inside the cylindrical hollow portion during theoperation of the compressing element. This provides a structure in whichoil is pulled by viscosity and also prevents abrasion and chipping dueto the contact and collision between the inner surface of thecylindrical hollow portion and the outer surface of the insertion memberwhich damages may lead to deterioration of the pumping ability and bringabout excessive abrasion and a locked condition of the compressingelement. Accordingly, long-term reliability can be secured.

Another advantage of the invention is that the components included arenot required to be fixed on the closed container. Since the insertionmember only floats inside the cylindrical hollow portion, lateralpressure due to fixation is scarcely applied between the cylindricalhollow portion and the insertion member and there is very fewpossibility of occurrence of sliding abrasion between the cylindricalhollow portion and the insertion member. Thus, a highly reliablecompressor which includes the viscous pump and is elastically supportedcan be provided.

In the above-described conventional structure, bracket 7115 andinsertion member 7120 engage with each other through longitudinal groove7521. Thus, the wall surface of the longitudinal groove of insertionmember 7120 collides with engagement portion 7523 of bracket 7115 atevery start-up, and the wall surface of the longitudinal groove is keptpressed thereon during continuous driving. As a result, abrasion occursdue to rubbing of the engagement portion, or bracket 7115 is twisted andthe stress is concentrated on the bended portion or other position ofbracket 7115, which causes fatigue to develop for a period of time.

When abrasion and fatigue thus caused further develop, thin filmprojections (extrusion) and depression of cracks (intrusion) occur atthe engagement portion and the bended portion. Especially, thedepression develops into visual minute cracks, which gradually spread tofinally cause corruption of bracket 7115. In this case, the rotation ofinsertion member 7120 inside sleeve 7112 may not be restricted.

Thus, it is difficult to maintain the structure of viscous pump 7113 ina stable condition for a long period of time.

For solving the above problem, an object of the present invention is toprovide a highly reliable compressor capable of maintaining thestructure of viscous pump 7113 for a long-term period without causingabrasion and fatigue by the contact between components at the time ofrestriction of the rotation of insertion member 7120.

Ninth and tenth embodiments according to the present invention are nowdescribed with reference to the drawings. However, the invention is notlimited to those embodiments.

Embodiment 9

FIG. 19 is a cross-sectional view illustrating a compressor in the ninthembodiment of the invention, and FIG. 20 is a cross-sectional viewillustrating a main part of the compressor in the ninth embodiment.

In FIGS. 19 and 20, oil 4102 is stored in closed container 4101 which isfilled with refrigerant gas 4103.

Compressing element 4110 includes: block 4115 which forms cylinder 4113;piston 4117 reciprocatively inserted into cylinder 4113; shaft 4125having main shaft portion 4120 supported by bearing 4116 of block 4115and eccentric portion 4122; and connecting rod 4119 for connectingeccentric portion 4122 and piston 4117. Compressing element 4110 forms areciprocating compressing mechanism.

Electrically-powered element 4135 is fixed below block 4115, andincludes stator 4136 connected to an inverter driving circuit (notshown) and rotor 4137 which contains permanent magnet and is fixed tomain shaft portion 4120. Electrically-powered element 4135 provides anelectric motor for driving the inverter, and is driven at a plurality ofdriving frequencies including those below 20 Hz, for example, by theinverter driving circuit (not shown).

Springs 4139 elastically support compressing element 4110 via stator4136 such that compressing element 4110 is elastically held on closedcontainer 4101.

Viscous pump 4140 soaked with oil 4102 is provided at the lower end ofmain shaft portion 4120 of shaft 4125.

Next, the structure of viscous pump 4140 is described in detail.

Cylindrical hollow portion 4141 is formed in main shaft portion 4120.Hollow sleeve 4142 is fixed to the lower region of cylindrical hollowportion 4141. Sleeve 4142 is substantially cylindrical and cap-shaped,whose top and bottom are open. Sleeve 4142 is made from iron plate pressmaterial which offers comparatively high accuracy in this embodiment,but may be formed from leaf spring steel.

Insertion member 4143 coaxially inserted into cylindrical hollow portion4141 and sleeve 4142 is made from a plastic material which has lowerthermal conductivity than the metal material which forms shaft 4125 andpossesses refrigerant-resistance and oil-resistance properties such asPPS, PBT, and PEEK. Spiral groove 4144 is engraved on the outer surfaceof insertion member 4143, whereby oil passage 4145 through which oilflows is provided between spiral groove 4144 and the inner surface ofsleeve 4142. The difference between the outermost diameter of insertionmember 4143 and the inside diameter of sleeve 4142, i.e., the matchingclearance is established in a range from 100 μm to 500 μm. Insertionmember 4143 has bolt hole 4146 at its upper end surface, and a pluralityof arms 4147 at its lower sides which extend substantially in thehorizontal direction.

Bolt 4150 is employed as supporting member 4152 for slidingly connectinginsertion member 4143 with sleeve 4142. Bolt 4150 inserted throughwasher 4151 penetrates bolt hole 4146 and reaches the upper surface ofcylindrical hollow portion 4141 to be attached thereto, therebyrotatably connecting insertion member 4143 to main shaft portion 4120 ofshaft 4125 and closing the lower end of bolt hole 4146. Washer 4151 ismade from a plastic material having high abrasion-resistance propertysuch as self-lubrication characteristic (PPS, PEE and PEEK etc.).Alternatively, bolt 4150 may be formed from a similar self-lubricationmaterial to eliminate washer 4151.

First permanent magnet 4148 is fixed to each arm 4147 which is disposedon the lower sides of insertion member 4143 to extend substantially inthe horizontal direction. Also, each second permanent magnet 4149 isprovided on the inner surface of the bottom of closed container 4101 viajoint 4153 such that the S-pole of second permanent magnet 4149 isopposed to the S-pole of first permanent magnet 4148 in the rotationaldirection with a predetermined space therebetween sufficiently withinthe reach of magnetic force. Alternatively, the N-poles of bothpermanent magnets 4148 and 4149 may be opposed to each other.

The operation of the compressor having the above structure is hereindescribed.

Main shaft portion 4120 rotates with the rotation of shaft 4125. Sleeve4142 fixed to main shaft portion 4120 rotates in synchronization withthe rotation of main shaft portion 4120. Insertion member 4143 is pulledby the rotation of sleeve 4142, but the rotation of insertion member4143 is prevented by the repulsion between the same poles of firstpermanent magnet 4148 provided on the insertion member and secondpermanent magnet 4149. As a result, oil rises through oil spiral passage4145 while rotating and being pulled by the inner surface of sleeve 4142due to viscosity.

At this stage, oil 4102 rises while rotating not only by the centrifugalforce which decreases at low-speed revolution but by a pulling forcegenerated by viscosity. Thus, oil 4102 can be drawn up in a stablemanner even at the time of low-speed revolution such as 600 rpm.

According to this embodiment as described above, the rotation ofinsertion member 4143 is prevented by a non-contact method utilizing therepulsion between first permanent magnet 4148 and second permanentmagnet 4149, causing no abrasion and fatigue by the contact between thecomponents in relation to the restriction of insertion member 4143.Accordingly, the structure of viscous pump 4140 is maintained in astable condition for a long period of time, and thus a highly reliablecompressor can be provided.

According to this embodiment, second permanent magnet 4149 is disposedin the vicinity of the inner surface of the bottom of closed container4101 for the structural reason of the compressor. Thus, joints 4153require not a complicated but an extremely simple structure so as tosecure second permanent magnet 4149 to closed container 4101.

Second permanent magnet 4149 is directly or indirectly fixed on closedcontainer 4101, but is kept prevented from contacting with firstpermanent magnet 4148 since the same poles are opposed. Consequently,sound and vibration generated from compressing element 4110 andelectrically-powered element 4135 are not transmitted though firstpermanent magnet 4148 and second permanent magnet 4149 to closedcontainer 4101.

According to this embodiment, insertion member 4143 is rotatablyconnected to main shaft portion 4120 of shaft 4125 by means of bolt 4150which is inserted through washer 4151. Thus, the position of insertionmember 4143 relative to sleeve 4142 fixed at the lower end of main shaftportion 4120 is determined by this connecting portion, and an almostconstant clearance is maintained between insertion member 4143 andsleeve 4142. This clearance is maintained by the fact that lateralpressure due to fixation is scarcely caused and also that the oilpressure is generated between insertion member 4143 and sleeve 4142.Accordingly, there is very few possibility of occurrence of slidingabrasion between insertion member 4143 and sleeve 4142.

Spiral groove 4144 is provided on the outer surface of insertion member4143 to form spiral oil passage 4145 in this embodiment, but may bedisposed on the inner surface of sleeve 4142 to form oil passage 4145.In this case, the area of the inner surface of the rotational body incontact with oil 4102 is enlarged by adding the surface area of theconcaves of the spiral groove. This structure causes large viscousresistance, thereby enhancing oil 4102 transfer capability. Moreover,centrifugal force generated through the rotation of main shaft portion4120 is applied to oil 4102 existing within the oil passage 4145 formedbetween the inner surface of sleeve 4142 and the outside surface ofinsertion member 4143, and the oil rises while rotating and incliningtoward the farthermost surface from the rotational shaft center in oilpassage 4145. Since there is no clearance in the position to which thecentrifugal force is most applied, oil does not fall to flow out andthus the amount of oil which falls to flow out can be decreased.Accordingly, the compressor in this embodiment obtains considerablyhigher oil transfer capability than the example in which spiral groove4144 is formed on insertion member 4143.

Embodiment 10

FIG. 21 is a cross-sectional view illustrating a compressor in a tenthembodiment of the invention, and FIG. 22 is a cross-sectional viewillustrating a main part of the compressor in the tenth embodiment.

The tenth embodiment is herein described with reference to FIGS. 21 and22. Similar numbers are given to the structures similar to those of theninth embodiment, and detailed description of those is omitted.

Viscous pump 4240 soaked with oil 4202 is provided at the lower end ofmain shaft portion 4120 of shaft 4125.

Next, the structure of viscous pump 4240 is described in detail.

Cylindrical hollow portion 4241 is formed in main shaft portion 4120.Hollow sleeve 4242 is fixed to the lower region of cylindrical hollowportion 4241. Sleeve 4242 is substantially cylindrical and cap-shaped,whose top and bottom are open. Sleeve 4242 is made from iron plate pressmaterial which offers comparatively high accuracy in this embodiment,but may be formed from leaf spring steel.

Insertion member 4243 coaxially inserted into cylindrical hollow portion4241 and sleeve 4242 is made from a plastic material which has lowerthermal conductivity than the metal material which forms shaft 4125 andpossesses refrigerant-resistance and oil-resistance properties such asPPS, PBT, and PEEK. Spiral groove 4244 is engraved on the outer surfaceof insertion member 4243, whereby oil passage 4245 through which oilflows is provided between spiral groove 4244 and the inner surface ofsleeve 4242. The difference between the outermost diameter of insertionmember 4243 and the inside diameter of sleeve 4242, i.e., the matchingclearance is established in a range from 100 μm to 500 μm. Insertionmember 4243 has bolt hole 4246 at its upper end surface, and a pluralityof arms 4247 at its lower sides which extend substantially in thehorizontal direction.

Bolt 4250 is employed as supporting member 4252 for slidingly connectinginsertion member 4243 with sleeve 4242. Bolt 4250 inserted throughwasher 4251 penetrates bolt hole 4246, and reaches the upper surface ofcylindrical hollow portion 4241 to be attached thereto, therebyrotatably connecting insertion member 4243 to main shaft portion 4120 ofshaft 4125 and closing the lower end of bolt hole 4246. Washer 4251 ismade from a plastic material having high abrasion-resistance propertysuch as self-lubrication characteristic (PPS and PEEK etc.).Alternatively, bolt 4250 may be formed from a similar self-lubricationmaterial to eliminate washer 4251.

First permanent magnet 4248 is fixed to each arm 4247 which is disposedon the lower sides of insertion member 4243 to extend substantially inthe horizontal direction. Also, each second permanent magnet 4249 isprovided such that the S-pole of second permanent magnet 4249 is opposedto the S-pole of first permanent magnet 4248 in the rotational directionwith a predetermined space therebetween sufficiently within the reach ofmagnetic force. Each second permanent magent 4249 is fixed on one end ofsubstantially L-shaped joint 4253 the other end of which is secured tothe lower region of stator 4136. The N-poles of both permanent magnets4248 and 4249 may be opposed to each other.

The operation of the compressor having the above structure is hereindescribed.

Main shaft portion 4120 rotates with the rotation of shaft 4125. Sleeve4242 fixed to main shaft portion 4120 rotates in synchronization withthe rotation of main shaft portion 4120. Insertion member 4243 is pulledby the rotation of sleeve 4242, but the rotation of insertion member4243 is prevented by the repulsion between the same poles of firstpermanent magnet 4248 provided on the insertion member and secondpermanent magnet 4249. As a result, oil rises through oil spiral passage4245 while rotating and being pulled by the inner surface of sleeve 4242due to viscosity.

At this stage, oil 4202 rises while rotating not only by the centrifugalforce which decreases at low-speed revolution but by a pulling forcegenerated by viscosity. Thus, oil can be drawn up in a stable mannereven at the time of low-speed revolution such as 600 rpm.

According to this embodiment as described above, the rotation ofinsertion member 4243 is restrained by a non-contact method through thesame mechanism as in the ninth embodiment, causing no abrasion andfatigue by the contact between the components in relation to therestriction of insertion member 4243. Accordingly, the structure ofviscous pump 4240 is maintained in a stable condition for a long periodof time, and thus a highly reliable compressor can be provided.

According to this embodiment, insertion member 4243 having firstpermanent magnets 4248 is connected to main shaft portion 4120 via bolt4250, and second permanent magnets 4249 are secured to the lower regionof stator 4136 via joints 4253. It is thus possible to attach all thecomponents included in viscous pump 4240 to electrically-powered element4135 or compressing element 4110 in advance, and assembly is facilitatedand productivity is enhanced by collectively installing those componentsin closed container 4101.

Second permanent magnets 4249 are fixed to the lower part ofelectrically-powered element 4135 having stator 4136 through joints 4253in this embodiment, but may be secured to any component of compressingelement 4110 such as block 4115 through joints 4253.

As described above, no abrasion and fatigue by the contact between thecomponents in relation to the restriction of the insertion member arecaused in the invention and the structure of the viscous pump ismaintained in a stable condition for a long period of time. Thus, ahighly reliable compressor can be provided.

In the invention, the structure is considerably simple and the secondpermanent magnets are kept prevented from contacting with the firstpermanent magnets since the same poles are opposed. As a result, soundand vibration generated from the compressing element and theelectrically-powered element are not transmitted through the firstpermanent magnets and the second permanent magnets to the outside of theclosed container, and thus a highly reliable compressor can be provided.

In the invention, it is possible to attach all the components includedin the viscous pump to the electrically-powered element or thecompressing element in advance and collectively install these componentsin the closed container. Accordingly, assembly is facilitated andproductivity is increased, and thus a highly reliable compressor can beprovided.

In the invention, generation of abnormal sound caused by vibration isprevented, and thus a highly reliable compressor can be provided.

In the invention, input to the compressor which drives at drivingfrequencies including at least in a range from 600 to 1,200 r/min. isreduced and the structure of the viscous pump is maintained in a stablecondition for a long period of time. Accordingly, power consumption islowered and thus a highly reliable compressor is provided.

In the invention, the rotation of the insertion member is prevented by anon-contact method utilizing repulsion between the permanent magnets.Accordingly, no abrasion and fatigue by the contact between thecomponents in relation to the restriction of the insertion member arecaused and the structure of the viscous pump is maintained in a stablecondition for a long period of time. Thus, a highly reliable compressorcan be provided.

The structure of the viscous pump can be maintained in a stablecondition for a long period of time by preventing the rotation of theinsertion member by a non-contact method, and thus a highly reliablecompressor can be provided.

In the conventional structure in which bracket 7115 supports the weightof insertion member 7120 at two points, insertion member 7120 insertedinto sleeve 7112 is inclined and contacts sleeve 7112. When bracket 7115does not have high dimensional accuracy or the center of gravity ofinsertion member 7120 is off the shaft center, the contact between theupper end of longitudinal groove 7621 provided at the lower end ofinsertion member 7120 and bracket 15 becomes a point contact. In thiscase, abrasion or fixation between sleeve 7112 and insertion member 7120may be caused, resulting in deterioration of the pumping ability andgeneration of abrasion powder which is circulated with oil toward thesliding area and caught between the sliding components and brings abouta locked condition of the compressing element.

An object of the present invention is to provide a highly reliablecompressor.

Eleventh through thirteenth embodiments are herein described withreference to the drawings. The invention is not limited to thoseembodiments.

Embodiment 11

FIG. 23 is a cross-sectional view illustrating a compressor in theeleventh embodiment of the invention, FIG. 24 is a cross-sectional viewillustrating a main part of the compressor in the eleventh embodiment,and FIG. 25 is an enlarged view illustrating a main part of an insertionmember in the eleventh embodiment.

In FIGS. 23, 24 and 25, oil 5102 is stored in closed container 5101which is filled with refrigerant gas 5103.

Compressing element 5110 includes: block 5115 which forms cylinder 5113;piston 5117 reciprocatively inserted into cylinder 5113; shaft 5125having main shaft portion 5120 supported by bearing 5116 of block 5115and eccentric portion 5122; and connecting rod 5119 for connectingeccentric portion 5122 and piston 5117. Compressing element 5110 forms areciprocating compressing mechanism.

Electrically-powered element 5135 is fixed below block 5115, andincludes stator 5136 connected to an inverter driving circuit (notshown) and rotor 5137 which contains permanent magnet and is fixed tomain shaft portion 5120. Electrically-powered element 5135 provides anelectric motor for driving an inverter, and is driven at a plurality ofdriving frequencies including those below 1,200 rpm, for example, by theinverter driving circuit (not shown).

Springs 5139 elastically support compressing element 5110 via stator5136 such that compressing element 5110 is elastically held on closedcontainer 5101.

Viscous pump 5140 soaked with oil 5102 is provided at the lower end ofmain shaft portion 5120 of shaft 5125.

Next, the structure of viscous pump 5140 is described in detail.

Hollow portion 5141 is formed in main shaft portion 5120. Hollow sleeve5142 is fixed to the lower region of hollow portion 5141 to formcylindrical hollow portion 5143. Sleeve 5142 is substantiallycylindrical and has a wall thickness in a range from about 0.5 mm toabout 11.0 mm. Sleeve 5142 is cap-shaped whose top and bottom are open.Sleeve 5142 is made from iron plate press material which offerscomparatively high accuracy in this embodiment, but may be formed fromleaf spring steel.

Insertion member 5144 coaxially inserted into cylindrical hollow portion5143 has a plurality of projections 5145 on its upper outside surface,and receiving portion 5146 at the upper end of sleeve 5142(corresponding to the thin-wall portion of sleeve 5142) rotatablyreceives the thrust surfaces of projections 5145 in a face contactcondition. The difference between the inside diameter of cylindricalhollow portion 5143 and the outermost diameter of projections 5145 isdetermined within a range from 0.1 mm to 0.5 mm. As for the method ofinstalling insertion member 5144, projections 5145 of insertion member5144 which has been inserted into sleeve 5142 in advance are disposed insuch a position as to be received by receiving portion 5146 at the upperend of sleeve 5142, and subsequently sleeve 5142 is fixed. By thismethod, installment of the insertion member can be simultaneouslycompleted. Alternatively, in a structure in which projections 5145 aredisposed on free joint 5154 which is elastically deformable in theradial direction, insertion member 5144 may be inserted and positionedafter sleeve 5142 is forcedly inserted into cylindrical hollow portion5141 and fixed thereto.

Insertion member 5144 is made from a synthetic resin material which haslower thermal conductivity than the metal material which forms shaft5125 and possesses refrigerant-resistance and oil-resistance propertiessuch as PPS, PBT, and PEEK. Spiral groove 5147 is engraved on the outersurface of insertion member 5144, whereby oil passage 5148 through whichoil flows is provided between spiral groove 5147 and the inner surfaceof sleeve 5142. The difference between the inside diameter of sleeve5142 and the outermost diameter of insertion member 5144 is almostequivalent to or slightly larger than the difference between the insidediameter of cylindrical hollow portion 5143 and the outermost diameterof projections 5145.

Substantially U-shaped bracket 5149 formed by an elastic body both endsof which are fixed to the lower region of stator 5136 are provided asmeans 5170 for preventing rotation of insertion member 5144. The centerof bracket 5149 engages with vertical groove 5150 provided at the lowerend of insertion member 5144 to support insertion member 5144 whilepreventing the rotation of insertion member.

Main shaft portion 5120 has hollow portion 5141 which includeslarge-diameter portion 5151 and small-diameter portion 5152. Insertionmember 5144 is supported inside cylindrical hollow portion 5143 whilebeing prevented from rising by disposing projections 5145 in such aposition as to be sandwiched between receiving portion 5146 and step5153 formed by large-diameter portion 5151 and small-diameter portion5152 with a certain clearance in the vertical direction.

The operation of the compressor having the above structure is nowdescribed.

Main shaft portion 5120 rotates with the rotation of shaft 5125.Cylindrical hollow portion 5143 rotates in synchronization with therotation of main shaft portion 5120. The thrust surfaces of projections5145 of insertion member 5144 are rotatably received by receivingportion 5146 formed on sleeve 5142. Insertion member 5144 is pulled bythe rotation of cylindrical hollow portion 5143, but the rotation ofinsertion member 5144 is prevented by bracket 5149.

As a result, oil rises through spiral oil passage 5148 while rotatingand being pulled by the inner surface of cylindrical hollow portion 5143due to viscosity. At this stage, oil 5102 rises while rotating not onlyby the centrifugal force which decreases at low-speed revolution but bya pulling force generated by viscosity. Thus, oil 5102 can be drawn upin a stable manner even at the time of low-speed revolution such as 600rpm.

According to this embodiment, the position of insertion member 5144relative to cylindrical hollow portion 5143 is determined by the surfacecontact between receiving portion 5146 and the thrust surfaces ofprojections 5145 provided on insertion member 5144. Accordingly, analmost constant clearance between insertion member 5144 and cylindricalhollow portion 5143 is maintained and thus excessive lateral pressurewhich may be produced by fixation is scarcely generated. As fluid filmpressure also develops within spiral groove 5147, there is very fewpossibility of occurrence of sliding abrasion between insertion member5144 and cylindrical hollow portion 5143.

Accordingly, it is possible to prevent generation of abrasion powderwhich is circulated with oil toward the sliding area and caught betweenthe sliding components and brings about a locked condition of thecompressing element, and thus a highly reliable compressor can beprovided.

In this embodiment, sleeve 5142 is fixed to hollow portion 5141 providedin the lower region of shaft 5125, and receiving portion 5146 is formedby the upper end of sleeve 5142 to effectively utilize the thin-wallregion of sleeve 5142 as receiving portion 5146. Thus, complicatedprocessing is not required to form sleeve 5142 and shaft 5125, and acompressor which is inexpensive and has high productivity can beprovided.

In this embodiment, insertion member 5144 including projections 5145,spiral groove 5147 and vertical groove 5150 is integrally formed from aself-lubricating synthetic resin. Thus, a compressor which isinexpensive and has high accuracy and high abrasion resistance can beprovided.

Spiral groove 5147 is formed on the outer surface of insertion member5144 to provide oil passage 5148 in this embodiment, but the spiralgroove may be disposed on the inner surface of sleeve 5142 to form oilpassage 5148. In this case, the area of the inner surface of therotational body in contact with oil is enlarged by adding the surfacearea of the concaves of the spiral groove. This structure causes largeviscous resistance, and thus oil transfer capability is enhanced.

Embodiment 12

FIG. 26 is a cross-sectional view illustrating a compressor in a twelfthembodiment of the invention, and FIG. 27 is a cross-sectional viewillustrating a main part of the compressor in the twelfth embodiment.

The twelfth embodiment is herein described with reference to FIGS. 26and 27. Similar numbers are given to the structures similar to those ofthe eleventh embodiment, and detailed description of those is omitted.

Viscous pump 5240 soaked with oil 5102 is provided at the lower end ofmain shaft portion 5220 of shaft 5125.

Next, the structure of viscous pump 5240 is described in detail.

Hollow portion 5241 is formed in main shaft portion 5220. Hollow sleeve5242 is inserted from outside and fixed to the lower region of hollowportion 5241 to form cylindrical hollow portion 5243. Sleeve 5242 issubstantially cylindrical and has large-diameter portion 5251 andsmall-diameter portion 5252. The wall thickness of sleeve 5242 isdetermined in a range from about 0.5 mm to about 1.0 mm. Sleeve 5242 iscap-shaped whose top and bottom are open. Sleeve 5242 is made from ironplate press material which offers comparatively high accuracy, but maybe formed from leaf spring steel.

Insertion member 5244 coaxially inserted into cylindrical hollow portion5243 has a plurality of projections 5245 on its upper outside surface,and receiving portion 5246 formed by a step between large-diameterportion 5251 and small-diameter portion 5252 of sleeve 5242 rotatablyreceives the thrust surfaces of projections 5245 in a face contactcondition. The thrust surface of receiving portion 5246 has a taperedshape, and the thrust surfaces of projections 5245 have tapered shapesin correspondence therewith. The difference between the inside diameterof receiving portion 5246 and the outermost diameter of projections 5245is determined within a range from 0.1 mm to 0.5 mm. As for the method ofinstalling insertion member 5244, projections 5245 of insertion member5244 which has been inserted into sleeve 5242 in advance are disposed insuch a position as to be received by receiving portion 5246 provided onthe upper end of sleeve 5242, and subsequently insertion member 5244 isinserted from outside and fixed. By this method, installment ofinsertion member 5244 can be simultaneously completed.

Insertion member 5244 is made from a synthetic resin material which haslower thermal conductivity than the metal material which forms shaft5125 and possesses refrigerant-resistance and oil-resistance propertiessuch as PPS, PBT, and PEEK. Spiral groove 5247 is engraved on the outersurface of insertion member 5244, whereby oil passage 5248 through whichoil flows is provided between spiral groove 5247 and the inner surfaceof sleeve 5242. The difference between the inside diameter of sleeve5242 and the outermost diameter of insertion member 5244 is almostequivalent to or slightly larger than the difference between the insidediameter of receiving portion 5246 and the outermost diameter ofprojections 5245.

A plurality of impellers 5249 as means 5270 for preventing rotation ofinsertion member 5244 are disposed at the lower sides of insertionmember 5244 to extend toward the periphery.

Insertion member 5244 is supported inside cylindrical hollow portion5243 while being prevented from rising by disposing projections 5245 insuch a position as to be sandwiched between the lower end of main shaftportion 5220 and receiving portion 5246 formed by large-diameter portion5251 and small-diameter portion 5252 with a certain clearance in thevertical direction.

The operation of the compressor having the above structure is nowdescribed.

Main shaft portion 5220 rotates with the rotation of shaft 5125.Cylindrical hollow portion 5243 rotates in synchronization with therotation of main shaft portion 5220. The thrust surfaces of projections5245 of insertion member 5244 are rotatably received by receivingportion 5246 formed by large-diameter portion 5251 of sleeve 5242 andsmall-diameter portion 5252. Insertion member 5244 is pulled by therotation of cylindrical hollow portion 5243, but rotates at a rotationalfrequency far lower than that of cylindrical hollow portion 5243 sinceimpellers 5249 receive large viscous resistance in the rotationaldirection within oil 5102. Thus, there is a difference in rotationalfrequency between cylindrical hollow portion 5243 and insertion member5244, which difference is near the rotational frequency of shaft 5125.

As a result, oil rises through spiral oil passage 5248 while rotatingand being pulled by the inner surface of cylindrical hollow portion 5243due to viscosity. At this stage, oil 5102 rises while rotating not onlyby the centrifugal force which decreases at low-speed revolution but bya pulling force generated by viscosity. Thus, oil can be drawn up in astable manner even at the time of low-speed revolution such as 600 rpm.

According to this embodiment, the position of insertion member 5244relative to cylindrical hollow portion 5243 is determined by the surfacecontact between receiving portion 5246 and the thrust surfaces ofprojections 5245 provided on insertion member 5244. Accordingly, analmost constant clearance between insertion member 5244 and cylindricalhollow portion 5243 is maintained and thus excessive lateral pressurewhich may be produced by fixation is scarcely generated. As fluid filmpressure is generated within spiral groove 5247 and generation of thefluid film pressure is promoted by providing the tapered thrust surfacesof projections 5245 and receiving portion 5246, there is very fewpossibility of occurrence of sliding abrasion between insertion member5244 and cylindrical hollow portion 5243.

Accordingly, it is possible to prevent generation of abrasion powderwhich is circulated with oil toward the sliding area and caught betweenthe sliding components and brings about a locked condition of thecompressing element, and thus a highly reliable compressor can beprovided.

In this embodiment, sleeve 5242 is fixed to hollow portion 5241 providedin the lower region of shaft 5125, and receiving portion 5246 is formedby large-diameter portion 5251 and small-diameter portion 5252 of sleeve5242 to effectively utilize the step of sleeve 5242 as receiving portion5246. Thus, complicated processing is not required to form shaft 5125and sleeve 5242, and a compressor which is inexpensive and has highproductivity can be provided.

Since the rotation of sleeve 5242 is prevented by large viscousresistance applied to impellers 5249 in the rotational direction withinoil 5102, indirect fixing of sleeve 5242 to stator 5136 or othercomponents is not needed and the structure is considerably simplifiedrequiring only a small number of components and processes. Thus, aviscous pump having high productivity can be provided.

Embodiment 13

FIG. 28 is a cross-sectional view illustrating a compressor in athirteenth embodiment of the invention, and FIG. 29 is a cross-sectionalview illustrating a main part of the compressor in the thirteenthembodiment.

The thirteenth embodiment is herein described with reference to FIGS. 28and 29. Similar numbers are given to the structures similar to those ofthe eleventh embodiment, and detailed description of those is omitted.

Viscous pump 5340 soaked with oil 5102 is provided at the lower end ofmain shaft portion 5320 of shaft 5125.

Next, the structure of viscous pump 5340 is described in detail.

Hollow portion 5341 is formed in main shaft portion 5320. Hollow sleeve5342 is inserted from outside and fixed to the lower region of hollowportion 5341 to form cylindrical hollow portion 5343. Sleeve 5342 issubstantially cylindrical and has large-diameter portion 5351 andsmall-diameter portion 5352. The wall thickness of sleeve 5342 isdetermined in a range from about 0.5 mm to about 11.0 mm. Sleeve 5342 iscap-shaped whose top and bottom are open, and is made from iron platepress material which offers comparatively high accuracy, but may beformed from leaf spring steel.

Insertion member 5344 coaxially inserted into cylindrical hollow portion5343 has a plurality of projections 5345 on its upper outside surface,and receiving portion 5346 formed by a step between large-diameterportion 5351 and small-diameter portion 5352 of sleeve 5342 rotatablyreceives the thrust surfaces of projections 5345 in a face contactcondition. The thrust surface of receiving portion 5346 has a taperedshape, and the thrust surfaces of projections 5345 have tapered shapesin correspondence therewith. The difference between the inside diameterof receiving portion 5346 and the outermost diameter of projections 5345is determined within a range from 0.1 mm to 0.5 mm.

Spiral groove 5347 is engraved on the outer surface of insertion member5344, whereby oil passage 5348 through which oil flows is providedbetween spiral groove 5347 and the inner surface of sleeve 5342. Thedifference between the inside diameter of sleeve 5342 and the outermostdiameter of insertion member 5344 is almost equivalent to or slightlylarger than the difference between the inside diameter of receivingportion 5346 and the outermost diameter of projections 5345. A pluralityof arms 5349 radially project from the lower sides of insertion member5344.

As means 5370 for preventing the rotation of insertion member 5344,permanent magnet 5350 is fixed on each arm 5349 formed on insertionmember 5344, and each permanent magnet 5360 is fixed to the innersurface of the bottom of closed container 5101 in such a position as tobe substantially opposed to each permanent magnet 5350 with a sufficientpredetermined clearance within the reach of mutual magnetic force. Theopposed surfaces of permanent magnet 5350 and permanent magnet 5360 havedifferent poles from each other.

Insertion member 5344 is supported inside cylindrical hollow portion5343 while being prevented from rising by disposing projections 5345 insuch positions as to be sandwiched between the lower end of main shaftportion 5320 and receiving portion 5346 formed by large-diameter portion5351 and small-diameter portion 5352 with a certain clearance in thevertical direction.

The operation of the compressor having the above structure is nowdescribed.

Main shaft portion 5320 rotates with the rotation of shaft 5125.Cylindrical hollow portion 5343 rotates in synchronization with therotation of main shaft portion 5320. The thrust surfaces of projections5345 of insertion member 5344 are rotatably received by receivingportion 5346 formed by large-diameter portion 5351 of sleeve 5342 andsmall-diameter portion 5352. Insertion member 5344 is pulled by therotation of cylindrical hollow portion 5343, but the rotation ofinsertion member 5344 is prevented since permanent magnets 5350 andpermanent magnets 5360 adhere to each other.

As a result, oil rises through spiral oil passage 5348 while rotatingand being pulled by the inner surface of cylindrical hollow portion 5343due to viscosity. At this stage, oil 5102 rises while rotating not onlyby the centrifugal force which decreases at low-speed revolution but bya pulling force generated by viscosity. Thus, oil can be drawn up in astable manner even at the time of low-speed revolution such as 600 rpm.

According to this embodiment, the position of insertion member 5344relative to cylindrical hollow portion 5343 is determined by the surfacecontact between receiving portion 5346 and the thrust surfaces ofprojections 5345 provided on insertion member 5344. Accordingly, analmost constant clearance between insertion member 5344 and cylindricalhollow portion 5343 is maintained and thus excessive lateral pressurewhich may be produced by fixation is scarcely generated. As fluid filmpressure is generated within spiral groove 5347 and generation of thefluid film pressure is promoted by providing the tapered thrust surfacesof projections 5345 and receiving portion 5346, there is very fewpossibility of occurrence of sliding abrasion between insertion member5344 and cylindrical hollow portion 5343.

Accordingly, it is possible to prevent generation of abrasion powderwhich is circulated with oil toward the sliding area and caught betweenthe sliding components and brings about a locked condition of thecompressing element, and thus a highly reliable compressor can beprovided.

Additionally, the rotation of insertion member 5344 is prevented bypermanent magnet 5350 fixed on each arm 5349 formed on insertion member5344 and permanent magnet 5360 each fixed to the inner surface of thebottom of closed container 5101 in such a position as to besubstantially opposed to each permanent magnet 5360 with a predeterminedclearance. As a result, indirect fixing of insertion member 5344 tostator 5136 or other components is not needed and the structure isconsiderably simplified requiring only a small number of components andprocesses. Accordingly, a viscous pump having high productivity can beprovided.

An example which utilizes adhering force of the permanent magnets isshown in this embodiment, but similar operation and advantage can beattained by utilizing repulsion force generated by disposing the samepoles of the permanent magnets in such positions as to be opposed toeach other in the rotational direction of shaft 5125 to prevent therotation of insertion member 5344.

In this embodiment, iron dust such as abrasion powder floating in oil5102 is collected by the permanent magnets which are disposed in oil5102. Accordingly, the dust is prevented in advance from being caughtbetween the components in the viscous pump or in the sliding areasduring oil circulation, and thus reliability can be enhanced.

According to the compressor of the invention, the position of theinsertion member relative to the sleeve is restricted and abrasion andfixation between the insertion member and the sleeve are scarcelycaused. Thus, a highly reliable compressor can be provided.

In the compressor of the invention, the position of the insertion memberrelative to the sleeve is determined by the surface contact between thethrust surfaces of the projections and the receiving portion.Accordingly, abrasion and fixation between the insertion member and thecylindrical hollow portion are scarcely caused and thus a highlyreliable compressor can be provided.

In the compressor of the invention, complicated processing is notrequired for forming the sleeve. Thus, a compressor which is inexpensiveand has high productivity and reliability can be provided.

In the compressor of the invention, the step formed on the sleeve isutilized as the receiving portion. Accordingly, complicated processingis not required for forming the shaft and thus a compressor which isinexpensive and has high productivity and reliability can be provided.

In the compressor of the invention, fluid film pressure is easilygenerated due to the oil having flowed into the clearance between theprojections and the receiving portion. Accordingly, the contact betweenthe projections and the receiving portion is prevented and thus acompressor having high durability and reliability can be provided.

In the compressor of the invention, the rotation of the insertion memberis prevented by a simple structure and the viscous pump is constructedin a reliable manner. Thus, a highly reliable compressor can beprovided.

In the compressor of the invention, a process for fixing the insertionmember is not required. Accordingly, a compressor which is easilyassembled and has high productivity and high reliability can beprovided.

In the compressor of the invention, the rotation of the insertion memberis securely restrained and iron dust such as abrasion powder iscollected by the magnets to prevent the dust from being caught betweenthe components in the viscous pump or in the sliding areas in advance.Thus, a highly reliable compressor can be provided.

In the compressor of the invention, the insertion member which isinexpensive and has high accuracy and high abrasion resistance isemployed. Thus, a highly reliable compressor can be provided.

In the compressor of the invention, vibration transmitted from thecompressing element including the viscous pump and theelectrically-powered element is reduced. Accordingly, generation ofabnormal sound caused by vibration is eliminated and thus a highlyreliable compressor can be provided.

In the compressor of the invention, oil supply is stabilized, and inputto the compressor is decreased since the electrically-powered element isdriven at driving frequencies including those lower than the powersource frequency. Accordingly, power consumption is reduced and thus ahighly reliable compressor can be provided.

In the above-described conventional structure, both ends of bracket 7115are fixed to stator 7106. Additionally, stopper 7623 for preventingrotation of insertion member 7120 is provided at a position extremelyclose to the rotational shaft center. As a result, moment generatedthrough the rotation applies large load to stopper 7623, thereby curvingbracket 7115 into a twisted condition starting from the position ofstopper 7623. If the twisted condition is continued, fatigue of materialdevelops especially at the position of stopper 7623, and thin filmprojections (extrusion) and depression of cracks (intrusion) finallyoccur. Particularly, the depression develops into visual minute cracks,which gradually spread to finally cause corruption of bracket 7115. Inthis case, the rotation of insertion member 7120 inside sleeve 7112 maynot be prevented.

Moreover, for dispersing the load applied on stopper 7623 or increasingthe fatigue resistance strength of stopper 7623, bracket 7115 isrequired to have a complicated shape. In this case, the cost of thecompressor is inevitably raised.

In order to solve these problems, an object of the present invention isto provide a compressor which is inexpensive and highly reliable, and iscapable of maintaining the structure of viscous pump 7113 in a stablecondition for a long period of time without causing material fatigue tothe components in relation to the restriction of insertion member 7120.

Fourteenth and fifteenth embodiments of the invention are hereinafterdescribed with reference to the drawings, and the invention is notlimited to those embodiments.

Embodiment 14

FIG. 30 is a cross-sectional view illustrating a compressor in afourteenth embodiment of the invention, FIG. 31 is a cross-sectionalview illustrating a main part of the compressor in the fourteenthembodiment, and FIG. 32 is a cross-sectional view illustrating a mainpart of a viscous pump in the fourteenth embodiment.

In FIGS. 30, 31 and 32, oil 6102 is stored in closed container 6101which is filled with refrigerant gas 6103.

Compressing element 6110 includes: block 6115 which forms cylinder 6113;piston 6117 reciprocatively inserted into cylinder 6113; shaft 6125having main shaft portion 6120 supported by bearing 6116 of block 6115and eccentric portion 6122; and connecting rod 6119 for connectingeccentric portion 6122 and piston 6117. Compressing element 6110 forms areciprocating compressing mechanism.

Electrically-powered element 6135 is fixed below block 6115, andincludes stator 6136 connected to an inverter driving circuit (notshown) and rotor 6137 which contains permanent magnet and is fixed tomain shaft portion 6120. Electrically-powered element 6135 provides anelectric motor for driving an inverter, and is driven at a plurality ofdriving frequencies including those below 1,200 rpm, for example, by theinverter driving circuit (not shown).

Springs 139 elastically support compressing element 6110 via stator 6136such that compressing element 6110 is elastically held on closedcontainer 6101.

Viscous pump 6140 soaked with oil 6102 is provided at the lower end ofmain shaft portion 6120 of shaft 6125.

Next, the structure of viscous pump 6140 is described in detail.

Cylindrical hollow portion 6141 is formed in main shaft portion 6120.Hollow sleeve 142 is fixed to the lower region of cylindrical hollowportion 6141. Sleeve 142 is substantially cylindrical and cap-shaped,whose top and bottom are open. Sleeve 142 is made from iron plate pressmaterial which offers comparatively high accuracy in this embodiment,but may be formed from leaf spring steel.

Insertion member 6143 coaxially inserted into cylindrical hollow portion6141 and sleeve 142 is made from a plastic material which has lowerthermal conductivity than the metal material which forms shaft 6125 andpossesses refrigerant-resistance and oil-resistance properties such asPPS, PBT, and PEEK. Spiral groove 6144 is engraved on the outer surfaceof insertion member 6143, whereby oil passage 6145 through which oilflows is provided between spiral groove 6144 and the inner surface ofsleeve 142. The difference between the outermost diameter of insertionmember 6143 and the inner surface of sleeve 142, i.e., the matchingclearance is established in a range from 100 μm to 500 μm. Insertionmember 6143 has bolt hole 6146 at its upper end, and a plurality offirst contacting members 6147 at its lower sides off the rotationalshaft center of shaft 6125.

Each second contacting member 6148 is fixed to the inner surface of thebottom of closed container 6101 in such a position as to be opposed toeach first contacting member 6147 in the rotational direction with asufficient predetermined clearance from rotating sleeve 142. Both firstcontacting members 6147 and second contacting members 6148 arecompletely soaked with oil 6102 stored in the bottom area of closedcontainer 6101. First contacting members 6147 are made from plastic andformed integrally with insertion member 6143, but may be formed byfixing metal wires or fragments, for example, to the lower region ofinsertion member 6143. Second contacting members 6148 are substantiallyL-shaped and made from elastic material such as metal wires andfragments.

Bolt 6150 is employed as supporting member 6152 for slidingly connectinginsertion member 6143 with sleeve 142. Bolt 6150 inserted through washer6151 penetrates bolt hole 6146, and reaches the upper surface ofcylindrical hollow portion 6141 to be attached thereto, therebyrotatably connecting insertion member 6143 to main shaft portion 6120 ofshaft 6125 and closing the lower end of bolt hole 6146. Washer 6151 ismade from a plastic material having high abrasion-resistance propertysuch as self-lubrication characteristic (PPS and PEEK etc.).Alternatively, bolt 6150 may be formed from a similar self-lubricationmaterial to eliminate washer 6151.

The operation of the compressor having the above structure is hereindescribed.

Main shaft portion 6120 rotates with the rotation of shaft 6125. Sleeve142 fixed to main shaft portion 6120 rotates in synchronization with therotation of main shaft portion 6120. Insertion member 6143 is pulled bythe rotation of sleeve 142, but the rotation of insertion member 6143 isprevented by the elastic contact between first contacting members 6147provided on insertion member 6143 and second contacting members 6148provided on closed container 6101. As a result, oil rises through spiraloil passage 6145 while rotating and being pulled by the inner surface ofsleeve 142 due to viscosity. At this stage, oil 6102 rises whilerotating not only by the centrifugal force which decreases at low-speedrevolution but by a pulling force generated by viscosity. Thus, oil canbe drawn up in a stable manner even at the time of low-speed revolutionsuch as 600 rpm.

In the embodiment as described above, first contacting members 6147 andsecond contacting members 6148 are disposed away from the rotationalshaft center of shaft 6125. This arrangement decreases load applied bythe moment which is generated through the rotation while firstcontacting members 6147 and second contacting members 6148 arecontacting each other. Also, as both the contacting members elasticallycontact with each other, impact received is absorbed and materialfatigue of the components in relation to the restriction of insertionmember 6143 is scarcely caused. Accordingly, the structure of viscouspump 6140 is maintained in a stable condition for a long period of time,and thus a highly reliable compressor can be provided. Moreover, firstcontacting members 6147 and second contacting members 6148 are notrequired to have a complicated shape for reducing the load applied bythe moment generated through the rotation at the time of the contact.Thus, a considerably simple and inexpensive compressor can be provided.

Since first contacting members 6147 and second contacting members 6148are soaked with oil 6102, impact caused at the time of the contactbetween the contacting members is reduced by the viscosity of oil 6102.Also, even if rubbing is caused between the contacting members due tovibration from compressing element 6110, abrasion does not develop owingto the lubricating function of oil 6102. Thus, reliability can befurther increased.

Second contacting members 6148 are formed by metal wires or fragments inthis embodiment, but may be made from nitrile rubber (NBR) which iscomparatively inexpensive and has oil-resistance andrefrigerant-resistance properties, if mineral oil or diester syntheticoil is used as oil 6102. The nitrile rubber may be L-shaped as in theembodiment, or may be disposed on the contact portions of the metalwires or fragments. Additionally, it is possible to reduce sound andvibration transmitted to the outside of closed container 6101 at thetime of the contact between the contacting members by utilizing theshock absorbing characteristic of the nitrile rubber.

According to this embodiment, insertion member 6143 is rotatablyconnected to main shaft portion 6120 of shaft 6125 by means of bolt 6150which is inserted through washer 6151. Thus, the position of insertionmember 6143 relative to sleeve 142 fixed at the lower end of main shaftportion 6120 is restricted by this connecting portion, and an almostconstant clearance is maintained between insertion member 6143 andsleeve 142. This clearance is maintained by the fact that lateralpressure due to fixation is scarcely caused and also by the oil pressuregenerated between insertion member 6143 and sleeve 142, and thus thereis very few possibility of occurrence of sliding abrasion betweeninsertion member 6143 and sleeve 142.

Spiral groove 6144 is provided on the outer surface of insertion member6143 to form spiral oil passage 6145 in this embodiment, but may bedisposed on the inner surface of sleeve 142 to form oil passage 6145. Inthis case, the area of the inner surface of the rotational body incontact with oil 6102 is enlarged by adding the surface area of theconcaves of the spiral groove. This structure causes large viscousresistance, thereby enhancing oil transfer capability.

Embodiment 15

FIG. 33 is a cross-sectional view illustrating a main part of acompressor in a fifteenth embodiment of the invention.

The fifteenth embodiment is herein described with reference to FIG. 33.Similar numbers are given to the structures similar to those of thefourteenth embodiment, and detailed description of those is omitted.

Insertion member 6143 coaxially inserted into sleeve 142 has a pluralityof first contacting members 6247 at its lower sides off the rotationalshaft center of shaft 6125.

Each second contacting member 6248 is fixed to the inner surface of thebottom of closed container 6101 in such a position as to be opposed toeach first contacting member 6247 in the rotational direction with asufficient predetermined clearance from rotating sleeve 142. Both firstcontacting members 6247 and second contacting members 6248 arecompletely soaked with oil 6102 stored in the bottom area of closedcontainer 6101. First contacting members 6247 are made from plastic andformed integrally with insertion member 6143, but may be formed byfixing metal wires or fragments, for example, to the lower region ofinsertion member 6143. Second contacting members 6148 are substantiallyL-shaped and made from elastic material such as metal wires andfragments. Each second contacting member 6248 has metal flat plate 6249disposed in such a position as to contact with the face of first contactmember 6247.

According to this embodiment, since the faces of first contactingmembers 6247 and second contacting members 6248 contact each other andalso receive viscous resistance of oil 6102, the face pressure issecurely and extremely decreased by a simple structure. Accordingly,chipping at the contact portion is prevented and thus reliability can befurther increased.

In this embodiment, each second contacting member 6148 has metal flatplate 6249 in this embodiment. However, flat plate 6249 may be made fromnitrile rubber (NBR) which is comparatively inexpensive and hasoil-resistance and refrigerant-resistance properties, or has a coilspring or other means on the contact portion of flat plate 6249 togreatly enhance its shock absorbing characteristic at the time of thecontact.

In the invention as described above, both the contacting members aredisposed away from the rotational shaft center. This arrangementdecreases load applied by the moment which is generated through therotation at the time of the contact. Also, as both the contactingmembers elastically contact with each other, impact received is absorbedand material fatigue of the components in relation to the restriction ofthe insertion member is scarcely caused. Accordingly, as the contactingmembers are not required to have a complicated structure for reducingthe load, the structure of the viscous pump is maintained in a stablecondition for a long period of time, and thus a compressor which isinexpensive and highly reliable can be provided.

In the invention, impact caused at the time of the contact between thecontacting members is reduced by the viscosity of oil. Also, even ifrubbing is caused between the contacting members due to vibration fromthe compressing element, abrasion does not develop. Thus, a compressorwhich is inexpensive and highly reliable can be provided.

In the invention, at least either the first contacting members or thesecond contacting members are made from elastic bodies. Accordingly, thenumber of the components included is decreased and thus a compressorwhich is inexpensive and highly reliable can be provided.

In the invention, the elastic body is interposed between the firstcontacting member and the second contacting member. As a result,comparatively large impact caused by the contact during assembly ortransportation of the compressor is reduced, and the positions of thesecond contacting members are not required to be accurately determined.Thus, a compressor which is inexpensive and highly reliable can beprovided.

According to the invention, since the faces of the first contactingmembers and the second contacting members contact each other, the facepressure is securely more decreased by a simple structure. Accordingly,chipping at the contact portion is prevented and thus a compressor whichis inexpensive and highly reliable can be provided.

INDUSTRIAL APPLICABILITY

A compressor provided according to the present invention is a highlyreliable compressor capable of transferring oil in a stable manner evenat the time of low-speed driving. Thus, the compressor is applicable tohousehold refrigerators, and also to refrigerant cycles indehumidifiers, showcases, vending machines and so forth.

1. A compressor comprising a closed container which stores oil andaccommodates a compressing element for compressing refrigerant and anelectrically-powered element for driving the compressing element,wherein: the electrically-powered element includes a stator and a rotor;the compressing element includes a shaft which extends in a verticaldirection and rotates, and a viscous pump which is formed inside theshaft and communicates with the oil; and the viscous pump having acylindrical hollow portion formed in the shaft, an insertion membercoaxially and rotatably inserted into the cylindrical hollow portion, aspiral groove formed between the inner surface of the cylindrical hollowportion and the outer surface of the insertion member along a directionwhere the oil rises, and prevention means for preventing rotation of theinsertion member.
 2. A compressor as set forth in claim 1, furthercomprising a second viscous pump connected to the upper region of theviscous pump.
 3. A compressor as set forth in claim 2, wherein thesecond viscous pump includes a lead groove engraved on the outer surfaceof a main shaft portion of the shaft and the inner surface of a mainbearing which supports the main shaft portion.
 4. A compressor as setforth in claim 2, further comprising restriction means for restrictingmovement of the insertion member in rotational and vertical directions.5. A compressor as set forth in claim 4, wherein the restriction meansmade from elastic metal wire engages with an engagement hole provided onthe insertion member and includes a supporting member whose end is fixedto the stator.
 6. A compressor as set forth in claim 4, wherein therestriction means includes at least one supporting member extending fromthe lower end of the insertion member in an almost horizontal direction,one end of the supporting member being fixed to the stator and the otherend of the supporting member being rotatably connected to the end of thesupporting member.
 7. A compressor as set forth in claim 4, wherein therestriction means is made from elastic metal wire and engages with anengagement groove concaved on the lower end of the insertion member, therestriction means including a supporting member whose end is fixed tothe lower region of the stator and a sliding portion formed by an upperbottom of the cylindrical hollow portion and the upper surface of theinsertion member.
 8. A compressor as set forth in claim 1, wherein aspiral groove is formed on the inner surface of the cylindrical hollowportion along a direction where the oil rises.
 9. A compressor as setforth in claim 8, wherein the spiral groove is formed by fixing a spiralcomponent to the inner surface of the cylindrical hollow portion.
 10. Acompressor as set forth in claim 8, further comprising a bracket whoseboth ends are fixed to the lower region of the stator and whose centerengages with the lower end of the insertion member to support theinsertion member.
 11. A compressor as set forth in claim 1, wherein theprevention means is an impeller formed on the insertion member toproduce viscous resistance between the impeller and the oil.
 12. Acompressor as set forth in claim 11, wherein the cylindrical hollowportion is formed in a sleeve fixed to the shaft.
 13. A compressor asset forth in claim 12, wherein the sleeve is substantially cylindricaland has an upper face, a top of the insertion member being rotatablyconnected with the upper face of the sleeve.
 14. A compressor as setforth in claim 12, wherein the sleeve is substantially cylindrical andhas a bottom face, a bottom of the insertion member being rotatablyconnected with the bottom face of the sleeve.
 15. A compressor as setforth in claim 1, wherein the prevention means includes a firstpermanent magnet disposed in the vicinity of the lower end of theinsertion member off the rotational shaft center of the shaft and asecond permanent magnet disposed such that the same poles of the firstpermanent magnet and the second permanent magnet are opposed to eachother in the rotational direction.
 16. A compressor as set forth inclaim 15, wherein the second permanent magnet is directly or indirectlyfixed to the closed container.
 17. A compressor as set forth in claim15, wherein the second permanent magnet is directly or indirectly fixedto the electrically-powered element or the compressing element.
 18. Acompressor as set forth in claim 1, wherein the prevention meansincludes a first contacting member disposed in the vicinity of the lowerend of the insertion member off the rotational shaft center of the shaftand a second contacting member directly or indirectly secured to theclosed container or the stator and so positioned as to be opposed to thefirst contacting member in the rotational direction, the preventionmeans being provided by bringing the first contacting member intoelastic contact with the second contacting member.
 19. A compressor asset forth in claim 18, wherein the first contacting member and thesecond contacting member are disposed within the oil.
 20. A compressoras set forth in claim 18, wherein an elastic body is interposed betweenthe first contacting member and the second contacting member.
 21. Acompressor as set forth in claim 18, wherein at least either the firstcontacting member or the second contacting member is made from anelastic body.
 22. A compressor as set forth in claim 18, wherein theface of the first contacting member contacts the face of the secondcontacting member.
 23. A compressor as set forth in claim 1, furthercomprising a sleeve fixed to the lower region of the shaft to providethe cylindrical hollow portion, a projection formed on the outer surfaceof the insertion member, and a receiving portion provided on the sleevefor rotatably receiving a thrust face of the projection.
 24. Acompressor as set forth in claim 23, wherein the sleeve is forcedlyinserted into a hollow portion provided in the lower region of the shaftand fixed to the hollow portion, the receiving portion being formed bythe upper end face of the sleeve.
 25. A compressor as set forth in claim23, wherein the sleeve has a large-diameter portion and a small-diameterportion, the receiving portion being formed by a step between thelarge-diameter portion and the small-diameter portion.
 26. A compressoras set forth in claim 25, wherein the receiving portion has a taperedthrust face shape.
 27. A compressor as set forth in claim 23, whereinthe insertion member is formed from one-piece synthetic resin.
 28. Acompressor as set forth in claim 2, wherein the electrically-poweredelement is driven at driving frequencies including those equal to orlower than a power source frequency.
 29. A compressor as set forth inclaim 2, wherein the compressor is driven at driving frequenciesincluding at least those in a range from 600 to 1,200 r/min.
 30. Acompressor as set forth in claim 2, wherein the compressing element iselastically supported within the closed container.
 31. A compressor asset forth in claim 2, wherein isobutene is used as refrigerant.